Intermediate film for laminated glasses, and laminated glass

ABSTRACT

Provided is an interlayer film for laminated glass with which double images in laminated glass can be significantly suppressed. An interlayer film for laminated glass according to the present invention has one end, and the other end having a larger thickness than the one end, and has a region for display corresponding to a display region of a head-up display, and when points are selected at 2 mm intervals while taking a position of 2 cm from an end part of the one end side toward the other end of the region for display as a start point, and a position of 2 cm from an end part of the other end side toward the one end of the region for display as an end point, and first partial wedge angles are calculated in respective first partial regions of 40 mm in the direction connecting the one end and the other end centered at respective selected points, an absolute value of difference between the maximum value among all the first partial wedge angle values and the minimum value among all the first partial wedge angle values is 0.4 mrad or less, and the interlayer film as a whole has a wedge angle of 0.1 mrad or more.

TECHNICAL FIELD

The present invention relates to an interlayer film for laminated glasswhich is used for obtaining laminated glass. Moreover, the presentinvention relates to laminated glass prepared with the interlayer filmfor laminated glass.

BACKGROUND ART

Since laminated glass generally generates only a small amount ofscattering glass fragments even when subjected to external impact andbroken, laminated glass is excellent in safety. As such, the laminatedglass is widely used for automobiles, railway vehicles, aircraft, ships,buildings and the like. The laminated glass is produced by sandwichingan interlayer film for laminated glass between a pair of glass plates.

Moreover, as the laminated glass used for automobiles, a head-up display(HUD) has been known. In a HUD, it is possible to display measuredinformation including automobile traveling data such as speed on thewindshield of the automobile, and the driver can recognize as if thedisplay were shown in front of the windshield.

In the HUD, there is a problem that the measured information or the likeis doubly observed.

In order to suppress double images, a wedge-shaped interlayer film hasbeen used. The following Patent Document 1 discloses a sheet oflaminated glass in which a wedge-shaped interlayer film having aprescribed wedge angle is sandwiched between a pair of glass plates. Insuch a sheet of laminated glass, by the adjustment of the wedge angle ofthe interlayer film, a display of measured information reflected by oneglass plate and a display of measured information reflected by the otherglass plate can be focused into one point to make an image in the visualfield of a driver. For that reason, the display of measured informationis hard to be observed doubly and the visibility of a driver is hardlyhindered.

RELATED ART DOCUMENT Patent Document

-   Patent Document 1: JP H4-502525 T

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In recent years, an attempt has been made to make the display positionrecognized by the driver be farther from the driver, for example, byincreasing the focal distance of the projector. However, in such adisplay, the display of measured information or the like can be morelikely to be observed doubly compared with the case where the displayposition is close to the driver.

In conventional interlayer films, it is difficult to sufficientlysuppress double image in the aforementioned case. Investigation carriedout by the present inventors led to the finding that only controlling awedge angle cannot sufficiently suppress double images in theaforementioned case.

An object of the present invention is to provide an interlayer film forlaminated glass with which double images can be significantly suppressedin laminated glass even when the display position is farther from thedriver. Moreover, the present invention also aims at providing laminatedglass prepared with the above-mentioned interlayer film for laminatedglass.

Means for Solving the Problems

According to a broad aspect of the present invention, there is providedan interlayer film for laminated glass (in this specification,“interlayer film for laminated glass” is sometimes abbreviated as“interlayer film”) for use in laminated glass that is a head-up display,the interlayer film having one end, and the other end being at theopposite side of the one end, the other end having a thickness largerthan a thickness of the one end, the interlayer film having a region fordisplay corresponding to a display region of the head-up display, whenpoints are selected at 2 mm intervals while taking a position of 2 cmfrom an end part of the one end side toward the other end of the regionfor display as a start point, and a position of 2 cm from an end part ofthe other end side toward the one end of the region for display as anend point, and first partial wedge angles are calculated in respectivefirst partial regions of 40 mm in the direction connecting the one endand the other end centered at respective selected points, an absolutevalue of difference between the maximum value among all the firstpartial wedge angle values and the minimum value among all the firstpartial wedge angle values being 0.4 mrad or less, the interlayer filmas a whole having a wedge angle of 0.1 mrad or more.

In a specific aspect of the interlayer film according to the presentinvention, when points are selected at 2 mm intervals while taking aposition of 2 cm from an end part of the one end side toward the otherend of the region for display as a start point, and a position of 2 cmfrom an end part of the other end side toward the one end of the regionfor display as an end point, and second partial wedge angles arecalculated in respective second partial regions of 20 mm in thedirection connecting the one end and the other end centered atrespective selected points, an absolute value of difference between themaximum value among all the second partial wedge angle values and theminimum value among all the second partial wedge angle values is 0.4mrad or less.

In a specific aspect of the interlayer film according to the presentinvention, when points are selected at 2 mm intervals while taking aposition of 2 cm from an end part of the one end side toward the otherend of the region for display as a start point, and a position of 2 cmfrom an end part of the other end side toward the one end of the regionfor display as an end point, and third partial wedge angles arecalculated in respective third partial regions of 10 mm in the directionconnecting the one end and the other end centered at respective selectedpoints, an absolute value of difference between the maximum value amongall the third partial wedge angle values and the minimum value among allthe third partial wedge angle values is 0.4 mrad or less.

According to a broad aspect of the present invention, there is providedan interlayer film for laminated glass having one end and the other endbeing at opposite side of the one end, the other end having a thicknessof larger than a thickness of the one end, when 250 points are selectedat 2 mm intervals from a position of 10 cm from the one end toward theother end of the interlayer film, and 250 first partial wedge angles arecalculated in respective first partial regions of 40 mm in the directionconnecting the one end and the other end centered at respective 250points, an absolute value of difference between the maximum value amongthe 250 first partial wedge angle values and the minimum value among the250 first partial wedge angle values being 0.4 mrad or less, theinterlayer film as whole having a wedge angle of 0.1 mrad or more.

In a specific aspect of the interlayer film according to the presentinvention, when 250 points are selected at 2 mm intervals from aposition of 10 cm from the one end toward the other end of theinterlayer film, and 250 second partial wedge angles are calculated inrespective second partial regions of 20 mm in the direction connectingthe one end and the other end centered at respective 250 points, anabsolute value of difference between the maximum value among the 250second partial wedge angle values and the minimum value among the 250second partial wedge angle values is 0.4 mrad or less.

In a specific aspect of the interlayer film according to the presentinvention, when 250 points are selected at 2 mm intervals from aposition of 10 cm from the one end toward the other end of theinterlayer film, and 250 third partial wedge angles are calculated inrespective third partial regions of 10 mm in the direction connectingthe one end and the other end centered at respective 250 points, anabsolute value of difference between the maximum value among the 250third partial wedge angle values and the minimum value among the 250third partial wedge angle values is 0.4 mrad or less.

It is preferred that the maximum value among the first partial wedgeangle values be 2.0 mrad or less. It is preferred that the maximum valueamong the second partial wedge angle values be 2.0 mrad or less. It ispreferred that the maximum value among the third partial wedge anglevalues be 2.0 mrad or less.

It is preferred that the minimum value among the first partial wedgeangle values be 0.1 mrad or more. It is preferred that the minimum valueamong the second partial wedge angle values be 0.1 mrad or more. It ispreferred that the minimum value among the third partial wedge anglevalues be 0.1 mrad or more.

It is preferred that the interlayer film contain a thermoplastic resin.It is preferred that the interlayer film contain a plasticizer.

In a specific aspect of the interlayer film according to the presentinvention, the interlayer film includes a first layer, and a secondlayer arranged on a first surface side of the first layer.

In a specific aspect of the interlayer film according to the presentinvention, the first layer contains a polyvinyl acetal resin, the secondlayer contains a polyvinyl acetal resin, and the content of the hydroxylgroup of the polyvinyl acetal resin in the first layer is lower than thecontent of the hydroxyl group of the polyvinyl acetal resin in thesecond layer.

In a specific aspect of the interlayer film according to the presentinvention, the first layer contains a polyvinyl acetal resin, the secondlayer contains a polyvinyl acetal resin, the first layer contains aplasticizer, the second layer contains a plasticizer, and the content ofthe plasticizer in the first layer relative to 100 parts by weight ofthe polyvinyl acetal resin in the first layer is larger than the contentof the plasticizer in the second layer relative to 100 parts by weightof the polyvinyl acetal resin in the second layer.

In a specific aspect of the interlayer film according to the presentinvention, the interlayer film has a portion with a sectional shape inthe thickness direction of a wedge-like shape in a region between aposition of 8 cm toward the other end from the one end and a position of61.8 cm toward the other end from the one end.

According to a broad aspect of the present invention, there is provideda laminated glass including a first lamination glass member, a secondlamination glass member and the interlayer film for laminated glassdescribed above, the interlayer film for laminated glass being arrangedbetween the first lamination glass member and the second laminationglass member.

Effect of the Invention

The interlayer film for laminated glass according to the presentinvention is an interlayer film for laminated glass for use in laminatedglass that is a head-up display. The interlayer film for laminated glassaccording to the present invention has one end and the other end beingat the opposite side of the one end. In the interlayer film forlaminated glass according to the present invention, the thickness of theother end is larger than the thickness of the one end. The interlayerfilm for laminated glass according to the present invention has, forexample, a region for display corresponding to a display region of ahead-up display. In the interlayer film for laminated glass according tothe present invention, points are selected at 2 mm intervals whiletaking a position of 2 cm from an end part of the one end side towardthe other end of the region for display as a start point, and a positionof 2 cm from an end part of the other end side toward the one end of theregion for display as an end point. In the interlayer film for laminatedglass according to the present invention, when first partial wedgeangles are calculated in respective first partial regions of 40 mm inthe direction connecting the one end and the other end centered atrespective selected points, an absolute value of difference between themaximum value among all the first partial wedge angle values and theminimum value among all the first partial wedge angle values is 0.4 mrador less. The interlayer film for laminated glass according to thepresent invention as a whole has a wedge angle of 0.1 mrad or more.Since the interlayer film for laminated glass according to the presentinvention is provided with the aforementioned configuration, it ispossible to significantly suppress double images in laminated glassprepared with the interlayer film for laminated glass according to thepresent invention.

The interlayer film for laminated glass according to the presentinvention has one end and the other end being at the opposite side ofthe one end. In the interlayer film for laminated glass according to thepresent invention, the thickness of the other end is larger than thethickness of the one end. In the interlayer film for laminated glassaccording to the present invention, 250 points are selected at 2 mmintervals from a position of 10 cm from the one end toward the other endof the interlayer film. In the interlayer film for laminated glassaccording to the present invention, when first partial wedge angles arecalculated in respective 250 first partial regions of 40 mm in thedirection connecting the one end and the other end centered atrespective 250 selected points, an absolute value of difference betweenthe maximum value among the 250 first partial wedge angle values and theminimum value among the 250 first partial wedge angle values is 0.4 mrador less. The interlayer film for laminated glass according to thepresent invention as a whole has a wedge angle of 0.1 mrad or more.Since the interlayer film for laminated glass according to the presentinvention is provided with the aforementioned configuration, it ispossible to significantly suppress double images in laminated glassprepared with the interlayer film for laminated glass according to thepresent invention.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1(a) and (b) are a sectional view and a front view, respectively,schematically showing an interlayer film for laminated glass, inaccordance with a first embodiment of the present invention.

FIGS. 2(a) and (b) are a sectional view and a front view, respectively,schematically showing an interlayer film for laminated glass, inaccordance with a second embodiment of the present invention.

FIG. 3 is a sectional view showing an example of laminated glassprepared with the interlayer film for laminated glass shown in FIG. 1 .

FIG. 4 is a perspective view schematically showing a roll body preparedby winding the interlayer film for laminated glass shown in FIG. 1 .

FIG. 5 is a figure for explaining a preliminary pressing method used inevaluation of double images in Examples.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, the details of the present invention will be described.

The interlayer film for laminated glass (in the present specification,sometimes abbreviated as “interlayer film”) according to the presentinvention is used for laminated glass.

The interlayer film according to the present invention has a one-layerstructure or a two or more-layer structure. The interlayer filmaccording to the present invention may have a one-layer structure andmay have a two or more-layer structure. The interlayer film according tothe present invention may have a two-layer structure, may have a two ormore-layer structure, may have a three-layer structure and may have athree or more-layer structure. The interlayer film according to thepresent invention may be a single-layered interlayer film and may be amulti-layered interlayer film.

The interlayer film according to the present invention has one end andthe other end being at the opposite side of the one end. The one end andthe other end are end portions of both sides facing each other in theinterlayer film. In the interlayer film according to the presentinvention, the thickness of the other end is larger than the thicknessof the one end.

The interlayer film according to the present invention has, for example,a region for display corresponding to a display region of a head-updisplay. The region for display is a region capable of favorablydisplaying information. A preferred range of the region for display willbe described later.

In the interlayer film according to the present invention, points areselected at 2 mm intervals while taking a position of 2 cm from an endpart of the one end side toward the other end of the region for displayas a start point, and a position of 2 cm from an end part of the otherend side toward the one end of the region for display as an end point.At this time, selection of points starts from an end part of the one endside, and points are selected up to the position where selection ofpositions at 2 mm intervals can be made from the one end side toward theother end side. Each partial region of 40 mm in the direction connectingthe one end and the other end, centered at each selected point isdefined as each first partial region (X1). The first partial region (X1)closest to the one end side of the interlayer film is a first partialregion (X1) of 0 cm to 4 cm from an end part of the one end side towardthe other end in the region for display, and the next first partialregion (X1) is a first partial region (X1) of 0.2 cm to 4.2 cm from anend part of the one end side toward the other end in the region fordisplay. Points are selected up to the position where the first partialregion (X1) can be selected. Neighboring two first partial regions (X1)overlap with each other by 38 mm in the direction connecting the one endand the other end.

A partial wedge angle at each first partial region (X1) (partial wedgeangle calculated at each first partial region (X1) is referred to asfirst partial wedge angle (θ1)) is calculated.

In the interlayer film according to the present invention, an absolutevalue of difference between the maximum value among all the firstpartial wedge angle (θ1) values, and the minimum value among all thefirst partial wedge angle (θ1) values is 0.4 mrad or less.

The interlayer film according to the present invention as a whole has awedge angle of 0.1 mrad or more.

Since the interlayer film according to the present invention is providedwith the aforementioned configuration, it is possible to significantlysuppress double images in laminated glass prepared with the interlayerfilm according to the present invention. In the present invention,generation of double images is significantly suppressed when the displayinformation from the display unit is reflected by the laminated glass.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between the maximum value among all the firstpartial wedge angle (θ1) values, and the minimum value among all thefirst partial wedge angle (θ1) values is preferably 0.35 mrad or less,more preferably 0.3 mrad or less, further preferably 0.25 mrad or less,especially preferably 0.2 mrad or less.

From the viewpoint of effectively suppressing double images, the maximumvalue among all the first partial wedge angle (θ1) values at the firstpartial regions (X1) is preferably 2.0 mrad or less, more preferably 1.8mrad or less, further preferably 1.5 mrad or less.

From the viewpoint of effectively suppressing double images, the minimumvalue among all the first partial wedge angle (θ1) values at the firstpartial regions (X1) is preferably 0.1 mrad or more, more preferably0.15 mrad or more, further preferably 0.2 mrad or more.

In the interlayer film according to the present invention, 250 pointsare selected at 2 mm intervals from a position of 10 cm from the one endtoward the other end of the interlayer film. Specifically, 250 pointsare selected at 2 mm intervals from a position of 10 cm from the one endtoward the other end, to a position of 59.8 cm from the one end towardthe other end. Respective 250 regions of 40 mm in the directionconnecting the one end and the other end, centered at respective 250selected points are defined as respective 250 first partial regions(X1). The first partial region (X1) closest to the one end side of theinterlayer film is a first partial region (X1) of 8 cm to 12 cm from theone end, and the next first partial region (X1) is a first partialregion (X1) of 8.2 cm to 12.2 cm from the one end. The farthest firstpartial region (X1) from the one end side of the interlayer film is afirst partial region (X1) of 57.8 to 61.8 cm from the one end.Neighboring two first partial regions (X1) overlap with each other by 38mm in the direction connecting the one end and the other end. Respective250 first partial regions (X1) are respective first partial regions (X1)of (8+0.2×A) cm to (12+0.2×A) cm from the one end (A is an integer of 0to 249).

Partial wedge angles at respective 250 first partial regions (X1)(partial wedge angle calculated at each first partial region (X1) isreferred to as first partial wedge angle (θ1)) are calculated.

In the interlayer film according to the present invention, an absolutevalue of difference between the maximum value among the 250 firstpartial wedge angle (θ1) values, and the minimum value among the 250first partial wedge angle (θ1) values is 0.4 mrad or less.

The interlayer film according to the present invention as a whole has awedge angle of 0.1 mrad or more.

Since the interlayer film according to the present invention is providedwith the aforementioned configuration, it is possible to significantlysuppress double images in laminated glass prepared with the interlayerfilm according to the present invention. In the present invention,generation of double images is significantly suppressed when the displayinformation from the display unit is reflected by the laminated glass.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between the maximum value among the 250 firstpartial wedge angle (θ1) values, and the minimum value among the 250first partial wedge angle (θ1) values is preferably 0.35 mrad or less,more preferably 0.3 mrad or less, further preferably 0.25 mrad or less,especially preferably 0.2 mrad or less.

From the viewpoint of effectively suppressing double images, the maximumvalue among the 250 first partial wedge angle (θ1) values at the firstpartial regions (X1) is preferably 2.0 mrad or less, more preferably 1.8mrad or less, further preferably 1.5 mrad or less.

From the viewpoint of effectively suppressing double images, the minimumvalue among the 250 first partial wedge angle (θ1) values at the firstpartial regions (X1) is preferably 0.1 mrad or more, more preferably0.15 mrad or more, further preferably 0.2 mrad or more.

One first partial wedge angle (θ1) is an interior angle at theintersection point of the following two lines. A line connecting surfaceparts of one side (first surface part) of the first partial region (X1)at an end part of the one end side and an end part of the other end sidein one first partial region (X1), and a line connecting surface parts ofthe other side (second surface part) of the interlayer film at an endpart of the one end side and an end part of the other end side in onefirst partial region (X1).

One first partial wedge angle (θ1) can be approximately calculated inthe following manner. Thickness of the interlayer film is measured ateach of the end part of the one end side and the end part of the otherend side of the first partial region (X1). On the basis of the result of(absolute value of difference between thickness at end part of one endside of first partial region (X1) and thickness at end part of the otherend side of first partial region (X1) (μm)÷40 (mm)), one first partialwedge angle (θ1) is approximately calculated.

In the interlayer film according to the present invention, points areselected at 2 mm intervals while taking a position of 2 cm from an endpart of the one end side toward the other end of the region for displayas a start point, and a position of 2 cm from an end part of the otherend side toward the one end of the region for display as an end point.At this time, selection of points starts from an end part of the one endside, and points are selected up to the position where selection ofpositions at 2 mm intervals can be made from the one end side toward theother end side. Each partial region of 20 mm in the direction connectingthe one end and the other end, centered at each selected point isdefined as each second partial region (X2). The second partial region(X2) closest to the one end side of the interlayer film is a secondpartial region (X2) of 1 cm to 3 cm from an end part of the one end sidetoward the other end in the region for display, and the next secondpartial region (X2) is a second partial region (X2) of 1.2 cm to 3.2 cmfrom an end part of the one end side toward the other end in the regionfor display. Points are selected up to the position where the secondpartial region (X2) can be selected. Neighboring two second partialregions (X2) overlap with each other by 18 mm in the directionconnecting the one end and the other end.

A partial wedge angle at each second partial region (X2) (partial wedgeangle calculated at each second partial region (X2) is referred to assecond partial wedge angle (θ2)) is calculated.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between the maximum value among all the secondpartial wedge angle (θ2) values, and the minimum value among all thesecond partial wedge angle (θ2) values is preferably 0.4 mrad or less,more preferably 0.35 mrad or less, further preferably 0.3 mrad or less,especially preferably 0.25 mrad or less.

From the viewpoint of effectively suppressing double images, the maximumvalue among all the second partial wedge angle (θ2) values at the secondpartial regions (X2) is preferably 2.0 mrad or less, more preferably 1.8mrad or less, further preferably 1.5 mrad or less.

From the viewpoint of effectively suppressing double images, the minimumvalue among all the second partial wedge angle (θ2) values at the secondpartial regions (X2) is preferably 0.1 mrad or more, more preferably0.15 mrad or more, further preferably 0.2 mrad or more.

In the interlayer film according to the present invention, 250 pointsare selected at 2 mm intervals from a position of 10 cm from the one endtoward the other end of the interlayer film. Specifically, 250 pointsare selected at 2 mm intervals from a position of 10 cm from the one endtoward the other end, to a position of 59.8 cm from the one end towardthe other end. Respective 250 second partial regions of 20 mm in thedirection connecting the one end and the other end, centered atrespective 250 selected points are defined as respective 250 secondpartial regions (X2). The second partial region (X2) closest to the oneend side of the interlayer film is a second partial region (X2) of 9 cmto 11 cm from the one end, and the next second partial region (X2) is asecond partial region (X2) of 9.2 cm to 11.2 cm from the one end. Thefarthest second partial region (X2) from the one end side of theinterlayer film is a second partial region (X2) of 58.8 to 60.8 cm fromthe one end. Neighboring two second partial regions (X2) overlap witheach other by 18 mm in the direction connecting the one end and theother end. Respective 250 second partial regions (X2) are respectivesecond partial regions (X2) of (9+0.2×A) cm to (11+0.2×A) cm from theone end (A is an integer of 0 to 249).

Partial wedge angles at respective 250 second partial regions (X2)(partial wedge angle calculated at each second partial region (X2) isreferred to as second partial wedge angle (θ2)) are calculated.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between the maximum value among the 250 secondpartial wedge angle (θ2) values, and the minimum value among the 250second partial wedge angle (θ2) values is preferably 0.4 mrad or less,more preferably 0.35 mrad or less, further preferably 0.3 mrad or less,especially preferably 0.25 mrad or less.

From the viewpoint of effectively suppressing double images, the maximumvalue among the 250 second partial wedge angle (θ2) values at the secondpartial regions (X2) is preferably 2.0 mrad or less, more preferably 1.8mrad or less, further preferably 1.5 mrad or less, especially preferably1.3 mrad or less.

From the viewpoint of effectively suppressing double images, the minimumvalue among the 250 second partial wedge angle (θ2) values at the secondpartial regions (X2) is preferably 0.1 mrad or more, more preferably0.15 mrad or more, further preferably 0.2 mrad or more.

One second partial wedge angle (θ2) is an interior angle at theintersection point of the following two lines. A line connecting surfaceparts of one side (first surface part) of the second partial region (X2)at an end part of the one end side and an end part of the other end sidein one second partial region (X2), and a line connecting surface partsof the other side (second surface part) of the interlayer film at an endpart of the one end side and an end part of the other end side in onesecond partial region (X2).

One second partial wedge angle (θ2) can be approximately calculated inthe following manner. Thickness of the interlayer film is measured ateach of the end part of the one end side and the end part of the otherend side of the second partial region (X2). On the basis of the resultof (absolute value of difference between thickness at end part of oneend side of second partial region (X2) and thickness at end part of theother end side of second partial region (X2) (μm)÷20 (mm)), one secondpartial wedge angle (θ2) is approximately calculated.

In the interlayer film according to the present invention, points areselected at 2 mm intervals while taking a position of 2 cm from an endpart of the one end side toward the other end of the region for displayas a start point, and a position of 2 cm from an end part of the otherend side toward the one end of the region for display as an end point.At this time, selection of points starts from an end part of the one endside, and points are selected up to the position where selection ofpositions at 2 mm intervals can be made from the one end side toward theother end side. Each partial region of 10 mm in the direction connectingthe one end and the other end, centered at each selected point isdefined as each third partial region (X3). The third partial region (X3)closest to the one end side of the interlayer film is a third partialregion (X3) of 1.5 cm to 2.5 cm from an end part of the one end sidetoward the other end in the region for display, and the next thirdpartial region (X3) is a third partial region (X3) of 1.7 cm to 2.7 cmfrom an end part of the one end side toward the other end in the regionfor display. Points are selected up to the position where the thirdpartial region (X3) can be selected. Neighboring two third partialregions (X3) overlap with each other by 8 mm in the direction connectingthe one end and the other end.

A partial wedge angle at each third partial region (X3) (partial wedgeangle calculated at each third partial region (X3) is referred to asthird partial wedge angle (θ3)) is calculated.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between the maximum value among all the thirdpartial wedge angle (θ3) values, and the minimum value among all thethird partial wedge angle (θ3) values is preferably 0.4 mrad or less,more preferably 0.38 mrad or less, further preferably 0.35 mrad or less,especially preferably 0.3 mrad or less.

From the viewpoint of effectively suppressing double images, the maximumvalue among all the third partial wedge angle (83) values at the thirdpartial regions (X3) is preferably 2.0 mrad or less, more preferably 1.8mrad or less, further preferably 1.5 mrad or less.

From the viewpoint of effectively suppressing double images, the minimumvalue among all the third partial wedge angle (θ3) values at the thirdpartial regions (X3) is preferably 0.1 mrad or more, more preferably0.15 mrad or more, further preferably 0.2 mrad or more.

One third partial wedge angle (θ3) is an interior angle at theintersection point of the following two lines. A line connecting surfaceparts of one side (first surface part) of the third partial region (X3)at an end part of the one end side and an end part of the other end sidein one third partial region (X3), and a line connecting surface parts ofthe other side (second surface part) of the interlayer film at an endpart of the one end side and an end part of the other end side in onethird partial region (X3).

One third partial wedge angle (θ3) can be approximately calculated inthe following manner. Thickness of the interlayer film is measured ateach of the end part of the one end side and the end part of the otherend side of the third partial region (X3). On the basis of the result of(absolute value of difference between thickness at end part of one endside of third partial region (X3) and thickness at end part of the otherend side of third partial region (X3) (μm)Γ10 (mm)), one third partialwedge angle (θ3) is approximately calculated.

In the interlayer film according to the present invention, 250 pointsare selected at 2 mm intervals from a position of 10 cm from the one endtoward the other end of the interlayer film. Specifically, 250 pointsare selected at 2 mm intervals from a position of 10 cm from the one endtoward the other end, to a position of 59.8 cm from the one end towardthe other end. Respective 250 regions of 10 mm in the directionconnecting the one end and the other end, centered at respective 250selected points are defined as respective 250 third partial regions(X3). The third partial region (X3) closest to the one end side of theinterlayer film is a third partial region (X3) of 9.5 cm to 10.5 cm fromthe one end, and the next third partial region (X3) is a third partialregion (X3) of 9.7 cm to 10.7 cm from the one end. The farthest thirdpartial region (X3) from the one end side of the interlayer film is athird partial region (X3) of 59.3 to 60.3 cm from the one end.Neighboring two third partial regions (X3) overlap with each other by 8mm in the direction connecting the one end and the other end. Respective250 third partial regions (X3) are respective third partial regions (X3)of (9.5+0.2×A) cm to (10.5+0.2×A) cm from the one end (A is an integerof 0 to 249).

Partial wedge angles at respective 250 third partial regions (X3)(partial wedge angle calculated at each third partial region (X3) isreferred to as third partial wedge angle (θ3)) are calculated.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between the maximum value among the 250 thirdpartial wedge angle (θ3) values, and the minimum value among the 250third partial wedge angle (θ3) values is preferably 0.4 mrad or less,more preferably 0.38 mrad or less, further preferably 0.35 mrad or less,especially preferably 0.3 mrad or less.

From the viewpoint of effectively suppressing double images, the maximumvalue among the 250 third partial wedge angle (θ3) values at the thirdpartial regions (X3) is preferably 2.0 mrad or less, more preferably 1.8mrad or less, further preferably 1.5 mrad or less, especially preferably1.3 mrad or less.

From the viewpoint of effectively suppressing double images, the minimumvalue among the 250 third partial wedge angle (θ3) values at the thirdpartial regions (X3) is preferably 0.1 mrad or more, more preferably0.15 mrad or more, further preferably 0.2 mrad or more.

From the viewpoint of suppressing the double images more effectively, itis preferred that the thickness increases from the one end toward theother end in a region of 80% or more (more preferably 85% or more,further preferably 90% or more, particularly preferably 95% or more) ofthe region between a position of 8 cm toward the other end from the oneend and a position of 61.8 cm toward the other end from the one end.From the viewpoint of suppressing the double images more effectively, itis preferred that the thickness increases from the one end toward theother end in a region of 80% or more (more preferably 85% or more,further preferably 90% or more, particularly preferably 95% or more) ofthe region between a position of 9 cm toward the other end from the oneend and a position of 60.8 cm toward the other end from the one end.From the viewpoint of suppressing the double images more effectively, itis preferred that the thickness increases from the one end toward theother end in a region of 80% or more (more preferably 85% or more,further preferably 90% or more, particularly preferably 95% or more) ofthe region between a position of 9.5 cm toward the other end from theone end and a position of 60.3 cm toward the other end from the one end.It is more preferred that the thickness increases from the one endtoward the other end in a region of 80% or more (more preferably 85% ormore, further preferably 90% or more, particularly preferably 95% ormore) of the region between a position of 10 cm toward the other endfrom the one end and a position of 59.8 cm toward the other end from theone end.

The interlayer film according to the present invention is suitably usedfor laminated glass serving as a head-up display (HUD). It is preferredthat the interlayer film according to the present invention be aninterlayer film for HUD.

A head-up display system can be obtained by using the aforementionedhead-up display. The head-up display system includes the laminatedglass, and a light source device for irradiating the laminated glasswith light for image display. The light source device can be attached,for example, to a dashboard in a vehicle. By irradiating the displayregion of the laminated glass with light from the light source device,it is possible to achieve image display.

It is preferred that the interlayer film according to the presentinvention have a region for display corresponding to a display region ofHUD. From the viewpoint of suppressing the double images moreeffectively, it is preferred that the interlayer film according to thepresent invention have the region for display in a region extending froma position of 8 cm from the one end toward the other end to a positionof 61.8 cm from the one end toward the other end. From the viewpoint ofsuppressing the double images more effectively, it is preferred that theinterlayer film according to the present invention have the region fordisplay in a region extending from a position of 9 cm from the one endtoward the other end to a position of 60.8 cm from the one end towardthe other end. From the viewpoint of suppressing the double images moreeffectively, it is preferred that the interlayer film according to thepresent invention have the region for display in a region extending froma position of 9.5 cm from the one end toward the other end to a positionof 60.3 cm from the one end toward the other end. It is more preferredthat the interlayer film according to the present invention have theregion for display in a region extending from a position of 10 cm fromthe one end toward the other end to a position of 59.8 cm from the oneend toward the other end. The region for display may exist in a part orthe whole of the region to the aforementioned position (for example,63.8 mm) from the one end toward the other end. The region for displaymay exist in a size of about 30 cm in the direction connecting the oneend and the other end.

From the viewpoint of suppressing the double images effectively, it ispreferred that the interlayer film have a portion with a sectional shapein the thickness direction of a wedge-like shape in the region between aposition of 8 cm toward the other end from the one end and a position of61.8 cm toward the other end from the one end. From the viewpoint ofsuppressing the double images effectively, it is preferred that theinterlayer film have a portion with a sectional shape in the thicknessdirection of a wedge-like shape in the region between a position of 9 cmtoward the other end from the one end and a position of 60.8 cm towardthe other end from the one end. From the viewpoint of suppressing thedouble images effectively, it is preferred that the interlayer film havea portion with a sectional shape in the thickness direction of awedge-like shape in the region between a position of 9.5 cm toward theother end from the one end and a position of 60.3 cm toward the otherend from the one end. It is more preferred that the interlayer film havea portion with a sectional shape in the thickness direction of awedge-like shape in the thickness direction in the region between aposition of 10 cm toward the other end from the one end and a positionof 59.8 cm toward the other end from the one end. The portion with asectional shape in the thickness direction of a wedge-like shape mayexist in a part or the whole of the region to the aforementionedposition (for example, 63.8 mm) from the one end toward the other end.The portion with a sectional shape in the thickness direction of awedge-like shape may exist in a size of about 30 cm in the directionconnecting the one end and the other end.

The interlayer film according to the present invention may have ashading region. The shading region may be separate from the region fordisplay. The shading region is provided so as to prevent a driver fromfeeling glare while driving, for example, by sunlight or outdoorlighting. The shading region can be provided so as to impart the heatblocking property. It is preferred that the shading region be located inan edge portion of the interlayer film. It is preferred that the shadingregion be belt-shaped.

In the shading region, a coloring agent or a filler may be used so as tochange the color and the visible light transmittance. The coloring agentor the filler may be contained in a partial region in the thicknessdirection of the interlayer film or may be contained in the entireregion in the thickness direction of the interlayer film.

From the viewpoint of providing better display, and further broadeningthe field of view, the visible light transmittance of the region fordisplay is preferably 80% or more, more preferably 88% or more, furtherpreferably 90% or more. It is preferred that the visible lighttransmittance of the region for display be higher than the visible lighttransmittance of the shading region. The visible light transmittance ofthe region for display may be lower than the visible light transmittanceof the shading region. The visible light transmittance of the region fordisplay is higher than the visible light transmittance of the shadingregion preferably by 50% or more, more preferably by 60% or more.

When the visible light transmittance varies in the interlayer film ofeach of the region for display and the shading region, the visible lighttransmittance is measured at the center position of the region fordisplay and at the center position of the shading region.

The visible light transmittance at a wavelength ranging from 380 to 780nm of the obtained laminated glass can be measured by using aspectrophotometer (“U-4100” available from Hitachi High-Tech ScienceCorporation) in conformity with JIS R3211 (1998). As the glass plate, itis preferred to use clear glass having a thickness of 2 mm.

It is preferred that the region for display have a length direction anda width direction. For excellent versatility of the interlayer film, itis preferred that the width direction of the region for display be thedirection connecting the one end and the other end. It is preferred thatthe region for display be belt-shaped.

It is preferred that the interlayer film has an MD direction and a TDdirection. For example, the interlayer film is obtained by meltextrusion molding. The MD direction is a flow direction of an interlayerfilm at the time of producing the interlayer film. The TD direction is adirection orthogonal to the flow direction of an interlayer film at thetime of producing the interlayer film and a direction orthogonal to thethickness direction of the interlayer film. It is preferred that the oneend and the other end be located on either side of the TD direction.

From the viewpoint of better display, it is preferred that theinterlayer film have a portion with a sectional shape of wedge-likeshape in the thickness direction. It is preferred that the sectionalshape in the thickness direction of the region for display be awedge-like shape.

Hereinafter, specific embodiments of the present invention will bedescribed with reference to the drawings.

FIGS. 1(a) and (b) are a sectional view and a front view, respectively,schematically showing an interlayer film for laminated glass inaccordance with a first embodiment of the present invention. FIG. 1(a)is a sectional view along the line I-I in FIG. 1(b). The size anddimension of the interlayer film in FIG. 1 and later described drawingsare appropriately changed from the actual size and shape for convenienceof illustration.

In FIG. 1(a), a section in the thickness direction of an interlayer film11 is shown. In this connection, in FIG. 1(a) and later describeddrawings, for convenience of illustration, the thicknesses of aninterlayer film and respective layers constituting the interlayer filmand the wedge angle (θ) are shown so as to be different from actualthicknesses thereof and an actual wedge angle.

The interlayer film 11 is provided with a first layer (intermediatelayer), a second layer 2 (surface layer), and a third layer 3 (surfacelayer). The second layer 2 is arranged on a first surface side of thefirst layer 1 to be layered thereon. The third layer 3 is arranged on asecond surface side opposite to the first surface of the first layer 1to be layered thereon. The first layer 1 is arranged between the secondlayer 2 and the third layer 3 to be sandwiched therebetween. Theinterlayer film 11 is used for obtaining laminated glass. The interlayerfilm 11 is an interlayer film for laminated glass. The interlayer film11 is a multilayer interlayer film.

The interlayer film 11 has one end 11 a and the other end 11 b at theopposite side of the one end 11 a. The one end 11 a and the other end 11b are end parts of both sides facing each other. The sectional shape inthe thickness direction of each of the second layer 2 and the thirdlayer 3 is a wedge-like shape. The sectional shape in the thicknessdirection of the first layer 1 is a rectangular shape. The thicknessesof the second layer 2 and the third layer 3 are larger in the other end11 b side than in the one end 11 a side. Accordingly, the thickness ofthe other end 11 b of the interlayer film 11 is larger than thethickness of the one end 11 a thereof. Accordingly, the interlayer film11 has a region being thin in thickness and a region being thick inthickness.

The interlayer film 11 has a region where the thickness increases fromthe one end 11 a side to the other end 11 b side. In the interlayer film11, the increment of the thickness is constant from the one end 11 aside to the other end 11 b side in the region where the thicknessincreases.

The interlayer film 11 has a region for display R1 corresponding to adisplay region of a head-up display. The interlayer film 11 has asurrounding region R2 neighboring the region for display R1. In thepresent embodiment, the region for display R1 is a region between aposition of 8 cm toward the other end 11 b from the one end 11 a and aposition of 61.8 cm toward the other end 11 b from the one end 11 a.

The interlayer film 11 has a shading region R3 that is separate from theregion for display R1. The shading region R3 is located in an edgeportion of the interlayer film 11.

The interlayer film has a shape as shown in FIG. 1(a), and may have aone-layer structure, a two-layer structure or four or more-layerstructure.

FIG. 4 is a perspective view schematically showing a roll body preparedby winding the interlayer film for laminated glass shown in FIG. 1 .

An interlayer film 11 may be wound to be formed into a roll body 51 ofthe interlayer film 11.

The roll body 51 shown in FIG. 4 is provided with a winding core 61 andthe interlayer film 11. The interlayer film 11 is wound around an outerperiphery of the winding core 61.

FIGS. 2(a) and (b) are a sectional view and a front view, respectively,schematically showing an interlayer film for laminated glass inaccordance with a second embodiment of the present invention. FIG. 2(a)is a sectional view along the line I-I in FIG. 2(b). In FIG. 2(a), asection in the thickness direction of an interlayer film 11A is shown.

The interlayer film 11A shown in FIG. 2 is provided with a first layer1A. The interlayer film 11A has a one-layer structure composed only ofthe first layer 1A and is a single-layered interlayer film. Theinterlayer film 11A is singly constituted by the first layer 1A. Theinterlayer film 11A is used for obtaining laminated glass. Theinterlayer film 11A is an interlayer film for laminated glass.

The interlayer film 11A has one end 11 a and the other end 11 b at theopposite side of the one end 11 a. The one end 11 a and the other end 11b are end parts of both sides facing each other. The thickness of theother end 11 b of the interlayer film 11A is larger than the thicknessof the one end 11 a thereof. Accordingly, the first layer 1A and theinterlayer film 11A have a region being thin in thickness and a regionbeing thick in thickness.

The interlayer film 11A has a region where the thickness increases fromthe one end 11 a side to the other end 11 b side. In the interlayer film11A, the increment of the thickness is constant from the one end 11 aside to the other end 11 b side in the region where the thicknessincreases.

The interlayer film 11A and the first layer 1A have portions 11Aa, 1Aahaving a rectangular sectional shape in the thickness direction, andportions 11Ab, 1Ab having a wedge-like sectional shape in the thicknessdirection.

The interlayer film 11A has a region for display R1 corresponding to adisplay region of a head-up display. The interlayer film 11A has asurrounding region R2 neighboring the region for display R1.

The interlayer film 11A has a shading region R3 that is separate fromthe region for display R1. The shading region R3 is located in an edgeportion of the interlayer film 11A.

The interlayer film has a shape as shown in FIG. 2(a) and may have a twoor more layer structure.

It is preferred that the interlayer film have a portion with a sectionalshape in the thickness direction of a wedge-like shape. It is preferredthat the interlayer film have a portion where the thickness graduallyincreases from one end toward the other end. It is preferred that thesectional shape in the thickness direction of the interlayer film be awedge-like shape. Examples of the sectional shape in the thicknessdirection of the interlayer film include a trapezoidal shape, atriangular shape, a pentagonal shape, and the like.

In the above-described interlayer film, the thickness may not increaseevenly from the one end toward the other end of the interlayer film. Theabove-described interlayer film may have a projecting portion on thesurface, or a recess portion on the surface.

In order to suppress double images, the wedge angle (θ) of theinterlayer film can be appropriately set according to the fitting angleof laminated glass. The wedge angle (θ) is a wedge angle in the entireinterlayer film. From the viewpoint of further suppressing doubleimages, the wedge angle (θ) of the interlayer film is 0.1 mrad (0.00575degrees) or more, more preferably 0.2 mrad (0.0115 degrees) or more.When the wedge angle (θ) is the above lower limit or more, it ispossible to obtain laminated glass suited for cars such as a truck or abus in which the attachment angle of the windshield is large.

From the viewpoint of further suppressing double images, the wedge angle(θ) of the interlayer film is preferably 2 mrad (0.1146 degrees) orless, and more preferably 0.7 mrad (0.0401 degrees) or less. When thewedge angle (θ) is the above upper limit or less, it is possible toobtain laminated glass suited for cars such as a sports car in which theattachment angle of the windshield is small.

The wedge angle (θ) of the interlayer film is an interior angle formedat the intersection point between a straight line connecting surfaceparts on the one side of the interlayer film (first surface part) of themaximum thickness part and the minimum thickness part in the interlayerfilm, and a straight line connecting surface parts of the other side ofthe interlayer film (second surface part) of the maximum thickness partand the minimum thickness part in the interlayer film. A wedge angle (θ)of the interlayer film can be approximately calculated in the followingmanner. Thickness of the interlayer film is measured at each of themaximum thickness part and the minimum thickness part. On the basis ofthe result of (absolute value of difference between thickness in maximumthickness part of interlayer film and thickness in minimum thicknesspart of interlayer film (μm)=distance between maximum thickness part andminimum thickness part (mm)), a wedge angle (θ) of the interlayer filmis approximately calculated.

When there are a plurality of maximum thicknesses parts, there are aplurality of minimum thicknesses parts, or the minimum thickness part islocated in a certain region, the maximum thickness part and the minimumthickness part for determining the wedge angle (θ) are selected so thatthe wedge angle (θ) to be determined is the maximum.

The thickness of the interlayer film is not particularly limited. Thethickness of the interlayer film refers to the total thickness of therespective layers constituting the interlayer film. Thus, in the case ofa multi-layered interlayer film 11, the thickness of the interlayer filmrefers to the total thickness of the first layer 1, the second layer 2,and the third layer 3.

The maximum thickness of the interlayer film is preferably 0.1 mm ormore, more preferably 0.25 mm or more, further preferably 0.5 mm ormore, especially preferably 0.8 mm or more and is preferably 3 mm orless, more preferably 2 mm or less, further preferably 1.5 mm or less.

A distance between the one end and the other end is defined as X. It ispreferred that the interlayer film have a minimum thickness in theregion at a distance of 0X to 0.2X inwardly from the one end, and amaximum thickness in the region at a distance of 0X to 0.2X inwardlyfrom the other end. It is more preferred that the interlayer film have aminimum thickness in the region at a distance of 0X to 0.1X inwardlyfrom the one end, and a maximum thickness in the region at a distance of0X to 0.1X inwardly from the other end. It is preferred that theinterlayer film have a minimum thickness at the one end and theinterlayer film have a maximum thickness at the other end.

The interlayer film 11, 11A has a maximum thickness at the other end 11b and a minimum thickness at the one end 11 a.

The interlayer film may have a uniform-thickness part. Theuniform-thickness part means that the variation in thickness does notexceed 10 μm per a distance range of 10 cm in the direction connectingthe one end and the other end of the interlayer film. Therefore, theuniform-thickness part refers to the part where the variation inthickness does not exceed 10 μm per a distance range of 10 cm in thedirection connecting the one end and the other end of the interlayerfilm. To be more specific, the uniform-thickness part refers to the partwhere the thickness does not vary at all in the direction connecting theone end and the other end of the interlayer film, or the thicknessvaries by 10 μm or less per a distance range of 10 cm in the directionconnecting the one end and the other end of the interlayer film.

From the viewpoint of the practical aspect and the viewpoint ofsufficiently enhancing the adhesive force and the penetrationresistance, the maximum thickness of a surface layer is preferably 0.001mm or more, more preferably 0.2 mm or more, further preferably 0.3 mm ormore, and is preferably 1 mm or less, and more preferably 0.8 mm orless.

From the viewpoint of the practical aspect and the viewpoint ofsufficiently enhancing the penetration resistance, the maximum thicknessof a layer (intermediate layer) arranged between two surface layers ispreferably 0.001 mm or more, more preferably 0.1 mm or more, and furtherpreferably 0.2 mm or more and is preferably 0.8 mm or less, morepreferably 0.6 mm or less, and further preferably 0.3 mm or less.

The distance X between one end and the other end of the interlayer filmis preferably 3 m or less, more preferably 2 m or less, especiallypreferably 1.5 m or less, and is preferably 0.5 m or more, morepreferably 0.8 m or more, especially preferably 1 m or more.

As a measuring device for use for measurement of a partial wedge angleof the interlayer film, a wedge angle (θ) of the interlayer film, and athickness of the interlayer film, a contact type thickness measuringinstrument “TOF-4R” (available from Yamabun Electronics Co., Ltd.) orthe like can be recited.

Measurement of the thickness is conducted so that the distance is theshortest from the one end toward the other end by using theabove-described measuring device at a film conveyance speed of 2.15 to2.25 mm/minutes.

As a measuring device for use for measurement of a partial wedge angleof the interlayer film, a wedge angle (θ) of the interlayer film, and athickness of the interlayer film after the interlayer film is made intolaminated glass, a non-contact type multilayer film thickness measuringinstrument “OPTIGAUGE” (available from Lumetrics, Inc.) or the like canbe recited. The thickness of the interlayer film can be measured whilethe interlayer film is in the laminated glass.

Hereinafter, the details of materials constituting the respective layersof a multi-layered interlayer film and the single-layered interlayerfilm will be described.

(Resin)

It is preferred that the interlayer film contain a resin. One kind ofthe resin may be used alone, and two or more kinds thereof may be usedin combination.

Examples of the resin include thermosetting resins and thermoplasticresins.

It is preferred that the interlayer film contain a resin (hereinafter,sometimes described as a resin (0)). It is preferred that the interlayerfilm contain a thermoplastic resin (hereinafter, sometimes described asa thermoplastic resin (0)). It is preferred that the interlayer filmcontain a polyvinyl acetal resin (hereinafter, sometimes described as apolyvinyl acetal resin (0)) as the thermoplastic resin (0). It ispreferred that the first layer contain a resin (hereinafter, sometimesdescribed as a resin (1)). It is preferred that the first layer containa thermoplastic resin (hereinafter, sometimes described as athermoplastic resin (1)). It is preferred that the first layer contain apolyvinyl acetal resin (hereinafter, sometimes described as a polyvinylacetal resin (1)) as the thermoplastic resin (1). It is preferred thatthe second layer contain a resin (hereinafter, sometimes described as aresin (2)). It is preferred that the second layer contain athermoplastic resin (hereinafter, sometimes described as a thermoplasticresin (2)). It is preferred that the second layer contain a polyvinylacetal resin (hereinafter, sometimes described as a polyvinyl acetalresin (2)) as the thermoplastic resin (2). It is preferred that thethird layer contain a resin (hereinafter, sometimes described as a resin(3)). It is preferred that the third layer contain a thermoplastic resin(hereinafter, sometimes described as a thermoplastic resin (3)). It ispreferred that the third layer contain a polyvinyl acetal resin(hereinafter, sometimes described as a polyvinyl acetal resin (3)) asthe thermoplastic resin (3). The resin (1), the resin (2), and the resin(3) may be the same as or different from one another. For still highersound insulating properties, it is preferred that the resin (1) bedifferent from the resin (2) and the resin (3). The thermoplastic resin(1), the thermoplastic resin (2), and the thermoplastic resin (3) may bethe same or different from one another. For still higher soundinsulating properties, it is preferred that the thermoplastic resin (1)be different from the thermoplastic resin (2) and the thermoplasticresin (3). Each of the polyvinyl acetal resin (1), the polyvinyl acetalresin (2) and the polyvinyl acetal resin (3) may be the same ordifferent from one another. For still higher sound insulatingproperties, it is preferred that the polyvinyl acetal resin (1) bedifferent from the polyvinyl acetal resin (2) and the polyvinyl acetalresin (3). One kind of each of the thermoplastic resin (0), thethermoplastic resin (1), the thermoplastic resin (2), and thethermoplastic resin (3) may be used alone and two or more kinds thereofmay be used in combination. One kind of each of the polyvinyl acetalresin (0), the polyvinyl acetal resin (1), the polyvinyl acetal resin(2), and the polyvinyl acetal resin (3) may be used alone and two ormore kinds thereof may be used in combination.

Examples of the thermoplastic resin include a polyvinyl acetal resin, apolyester resin, an ethylene-vinyl acetate copolymer resin, anethylene-acrylic acid copolymer resin, a polyurethane resin, a polyvinylalcohol resin, and the like. Thermoplastic resins other than these maybe used. The polyoxymethylene (or polyacetal) resin is included in thepolyvinyl acetal resin.

It is preferred that the resin be a thermoplastic resin. Thethermoplastic resin is more preferably a polyvinyl acetal resin or apolyester resin, and is further preferably a polyvinyl acetal resin. Byusing a polyvinyl acetal resin and a plasticizer together, the adhesiveforce of a layer containing the polyvinyl acetal resin and theplasticizer to a lamination glass member or another layer is furtherenhanced. It is preferred that the polyvinyl acetal resin be a polyvinylbutyral resin.

For example, the polyvinyl acetal resin can be produced by acetalizingpolyvinyl alcohol (PVA) with an aldehyde. It is preferred that thepolyvinyl acetal resin be an acetalized product of polyvinyl alcohol.For example, the polyvinyl alcohol can be obtained by saponifyingpolyvinyl acetate. The saponification degree of the polyvinyl alcoholgenerally lies within the range of 70 to 99.9% by mole.

The average polymerization degree of the polyvinyl alcohol (PVA) ispreferably 200 or more, more preferably 500 or more, even morepreferably 1500 or more, further preferably 1600 or more, especiallypreferably 2600 or more, most preferably 2700 or more and is preferably5000 or less, more preferably 4000 or less, further preferably 3500 orless. When the average polymerization degree is the above lower limit ormore, the penetration resistance of laminated glass is further enhanced.When the average polymerization degree is the above upper limit or less,formation of an interlayer film is facilitated.

The average polymerization degree of the polyvinyl alcohol is determinedby a method in accordance with JIS K6726 “Testing methods for polyvinylalcohol”.

The number of carbon atoms of the acetal group contained in thepolyvinyl acetal resin is not particularly limited. The aldehyde used atthe time of producing the polyvinyl acetal resin is not particularlylimited. It is preferred that the number of carbon atoms of the acetalgroup in the polyvinyl acetal resin fall within the range of 3 to 5 andit is more preferred that the number of carbon atoms of the acetal groupbe 3 or 4. When the number of carbon atoms of the acetal group in thepolyvinyl acetal resin is 3 or more, the glass transition temperature ofthe interlayer film is sufficiently lowered. The number of carbon atomsof the acetal group in the polyvinyl acetal resin may be 4 or 5.

Aldehyde is not particularly limited. In general, an aldehyde with 1 to10 carbon atoms is preferably used. Examples of the aldehyde with 1 to10 carbon atoms include formaldehyde, acetaldehyde, propionaldehyde,n-butyraldehyde, isobutyraldehyde, n-valeraldehyde,2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde,n-decylaldehyde, benzaldehyde, and the like. Propionaldehyde,n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde, or n-valeraldehydeis preferred, propionaldehyde, n-butyraldehyde, or isobutyraldehyde ismore preferred, and n-butyraldehyde is further preferred. One kind ofthe aldehyde may be used alone, and two or more kinds thereof may beused in combination.

The content of the hydroxyl group (the amount of hydroxyl groups) of thepolyvinyl acetal resin (0) is preferably 15% by mole or more and morepreferably 18% by mole or more and is preferably 40% by mole or less andmore preferably 35% by mole or less. When the content of the hydroxylgroup is the above lower limit or more, the adhesive force of theinterlayer film is further enhanced. Moreover, when the content of thehydroxyl group is the above upper limit or less, the flexibility of theinterlayer film is enhanced and the handling of the interlayer film isfacilitated.

The content of the hydroxyl group (hydroxyl group amount) of thepolyvinyl acetal resin (1) is preferably 17% by mole or more, morepreferably 20% by mole or more, and further preferably 22% by mole ormore. The content of the hydroxyl group (the amount of hydroxyl groups)of the polyvinyl acetal resin (1) is preferably 30% by mole or less,more preferably 28% by mole or less, still more preferably 27% by moleor less, further preferably 25% by mole or less, especially preferablyless than 25% by mole, especially preferably 24% by mole or less. Whenthe content of the hydroxyl group is the above lower limit or more, themechanical strength of the interlayer film is further enhanced. Inparticular, when the content of the hydroxyl group of the polyvinylacetal resin (1) is 20% by mole or more, the resin is high in reactionefficiency and is excellent in productivity, when being 28% by mole orless, the sound insulating properties of laminated glass are furtherenhanced, and when being 28% by mole or less, the sound insulatingproperties are further enhanced. Moreover, when the content of thehydroxyl group is the above upper limit or less, the flexibility of theinterlayer film is enhanced and the handling of the interlayer film isfacilitated.

Each of the contents of the hydroxyl group of the polyvinyl acetal resin(2) and the polyvinyl acetal resin (3) is preferably 25% by mole ormore, more preferably 28% by mole or more, more preferably 30% by moleor more, still more preferably more than 31% by mole, further preferably31.5% by mole or more, further preferably 32% by mole or more, andespecially preferably 33% by mole or more. Each of the contents of thehydroxyl group of the polyvinyl acetal resin (2) and the polyvinylacetal resin (3) is preferably 38% by mole or less, more preferably 37%by mole or less, further preferably 36.5% by mole or less, especiallypreferably 36% by mole or less. When the content of the hydroxyl groupis the above lower limit or more, the adhesive force of the interlayerfilm is further enhanced. Moreover, when the content of the hydroxylgroup is the above upper limit or less, the flexibility of theinterlayer film is enhanced and the handling of the interlayer film isfacilitated.

From the viewpoint of further enhancing the sound insulating properties,it is preferred that the content of the hydroxyl group of the polyvinylacetal resin (1) be lower than the content of the hydroxyl group of thepolyvinyl acetal resin (2). From the viewpoint of further enhancing thesound insulating properties, it is preferred that the content of thehydroxyl group of the polyvinyl acetal resin (1) be lower than thecontent of the hydroxyl group of the polyvinyl acetal resin (3). Fromthe viewpoint of still further enhancing the sound insulatingproperties, the absolute value of a difference between the content ofthe hydroxyl group of the polyvinyl acetal resin (1) and the content ofthe hydroxyl group of the polyvinyl acetal resin (2) is preferably 1% bymole or more, more preferably 5% by mole or more, further preferably 9%by mole or more, especially preferably 10% by mole or more, mostpreferably 12% by mole or more. From the viewpoint of still furtherenhancing the sound insulating properties, the absolute value of adifference between the content of the hydroxyl group of the polyvinylacetal resin (1) and the content of the hydroxyl group of the polyvinylacetal resin (3) is preferably 1% by mole or more, more preferably 5% bymole or more, further preferably 9% by mole or more, especiallypreferably 10% by mole or more, most preferably 12% by mole or more. Anabsolute value of difference between the content of the hydroxyl groupof the polyvinyl acetal resin (1) and the content of the hydroxyl groupof the polyvinyl acetal resin (2) is preferably 20% by mole or less. Anabsolute value of difference between the content of the hydroxyl groupof the polyvinyl acetal resin (1) and the content of the hydroxyl groupof the polyvinyl acetal resin (3) is preferably 20% by mole or less.

The content of the hydroxyl group of the polyvinyl acetal resin is amole fraction, represented in percentage, obtained by dividing theamount of ethylene groups to which the hydroxyl group is bonded by thetotal amount of ethylene groups in the main chain. For example, theamount of ethylene groups to which the hydroxyl group is bonded can bedetermined in accordance with JIS K6728 “Testing methods for polyvinylbutyral”.

The acetylation degree (the amount of acetyl groups) of the polyvinylacetal resin (0) is preferably 0.1% by mole or more, more preferably0.3% by mole or more, further preferably 0.5% by mole or more and ispreferably 30% by mole or less, more preferably 25% by mole or less,further preferably 20% by mole or less. When the acetylation degree isthe above lower limit or more, the compatibility between the polyvinylacetal resin and a plasticizer is enhanced. When the acetylation degreeis the above upper limit or less, with regard to the interlayer film andlaminated glass, the moisture resistance thereof is enhanced.

The acetylation degree (the amount of acetyl groups) of the polyvinylacetal resin (1) is preferably 0.01% by mole or more, more preferably0.1% by mole or more, even more preferably 7% by mole or more, furtherpreferably 9% by mole or more and is preferably 30% by mole or less,more preferably 25% by mole or less, further preferably 24% by mole orless, especially preferably 20% by mole or less. When the acetylationdegree is the above lower limit or more, the compatibility between thepolyvinyl acetal resin and a plasticizer is enhanced. When theacetylation degree is the above upper limit or less, with regard to theinterlayer film and laminated glass, the moisture resistance thereof isenhanced. In particular, when the acetylation degree of the polyvinylacetal resin (1) is 0.1% by mole or more and is 25% by mole or less, theresulting laminated glass is excellent in penetration resistance.

The acetylation degree of each of the polyvinyl acetal resin (2) and thepolyvinyl acetal resin (3) is preferably 0.01% by mole or more and morepreferably 0.5% by mole or more and is preferably 10% by mole or lessand more preferably 2% by mole or less. When the acetylation degree isthe above lower limit or more, the compatibility between the polyvinylacetal resin and a plasticizer is enhanced. When the acetylation degreeis the above upper limit or less, with regard to the interlayer film andlaminated glass, the moisture resistance thereof is enhanced.

The acetylation degree is a mole fraction, represented in percentage,obtained by dividing the amount of ethylene groups to which the acetylgroup is bonded by the total amount of ethylene groups in the mainchain. For example, the amount of ethylene groups to which the acetylgroup is bonded can be determined in accordance with JIS K6728 “Testingmethods for polyvinyl butyral”.

The acetalization degree of the polyvinyl acetal resin (0) (thebutyralization degree in the case of a polyvinyl butyral resin) ispreferably 60% by mole or more and more preferably 63% by mole or moreand is preferably 85% by mole or less, more preferably 75% by mole orless, further preferably 70% by mole or less. When the acetalizationdegree is the above lower limit or more, the compatibility between thepolyvinyl acetal resin and a plasticizer is enhanced. When theacetalization degree is the above upper limit or less, the reaction timerequired for producing the polyvinyl acetal resin is shortened.

The acetalization degree of the polyvinyl acetal resin (1) (thebutyralization degree in the case of a polyvinyl butyral resin) ispreferably 47% by mole or more and more preferably 60% by mole or moreand is preferably 85% by mole or less, more preferably 80% by mole orless, further preferably 75% by mole or less. When the acetalizationdegree is the above lower limit or more, the compatibility between thepolyvinyl acetal resin and a plasticizer is enhanced. When theacetalization degree is the above upper limit or less, the reaction timerequired for producing the polyvinyl acetal resin is shortened.

The acetalization degree of each of the polyvinyl acetal resin (2) andthe polyvinyl acetal resin (3) (the butyralization degree in the case ofa polyvinyl butyral resin) is preferably 55% by mole or more and morepreferably 60% by mole or more and is preferably 75% by mole or less andmore preferably 71% by mole or less. When the acetalization degree isthe above lower limit or more, the compatibility between the polyvinylacetal resin and a plasticizer is enhanced. When the acetalizationdegree is the above upper limit or less, the reaction time required forproducing the polyvinyl acetal resin is shortened.

The acetalization degree is determined in the following manner. From thetotal amount of the ethylene group in the main chain, the amount of theethylene group to which the hydroxyl group is bonded and the amount ofthe ethylene group to which the acetyl group is bonded are subtracted.The obtained value is divided by the total amount of the ethylene groupin the main chain to obtain a mole fraction. The mole fractionrepresented in percentage is the acetalization degree.

In this connection, it is preferred that the content of the hydroxylgroup (the amount of hydroxyl groups), the acetalization degree (thebutyralization degree) and the acetylation degree be calculated from theresults determined by a method in accordance with JIS K6728 “Testingmethods for polyvinyl butyral”. In this context, a method in accordancewith ASTM D1396-92 may be used. When the polyvinyl acetal resin is apolyvinyl butyral resin, the content of the hydroxyl group (the amountof hydroxyl groups), the acetalization degree (the butyralizationdegree) and the acetylation degree can be calculated from the resultsmeasured by a method in accordance with JIS K6728 “Testing methods forpolyvinyl butyral”.

(Plasticizer)

From the viewpoint of further enhancing the adhesive force of aninterlayer film, it is preferred that the interlayer film according tothe present invention contain a plasticizer (hereinafter, sometimesdescribed as a plasticizer (0)). It is preferred that the first layercontain a plasticizer (hereinafter, sometimes described as a plasticizer(1)). It is preferred that the second layer contain a plasticizer(hereinafter, sometimes described as a plasticizer (2)). It is preferredthat the third layer contain a plasticizer (hereinafter, sometimesdescribed as a plasticizer (3)). When the thermoplastic resin containedin the interlayer film is a polyvinyl acetal resin, it is especiallypreferred that the interlayer film (the respective layers) contain aplasticizer. It is preferred that a layer containing a polyvinyl acetalresin contain a plasticizer.

The plasticizer is not particularly limited. As the plasticizer, aconventionally known plasticizer can be used. One kind of theplasticizer may be used alone, and two or more kinds thereof may be usedin combination.

Examples of the plasticizer include organic ester plasticizers such as amonobasic organic acid ester and a polybasic organic acid ester, organicphosphate plasticizers such as an organic phosphate plasticizer and anorganic phosphite plasticizer, and the like. Organic ester plasticizersare preferred. It is preferred that the plasticizer be a liquidplasticizer.

Examples of the monobasic organic acid ester include a glycol esterobtained by the reaction of a glycol with a monobasic organic acid, andthe like. Examples of the glycol include triethylene glycol,tetraethylene glycol, tripropylene glycol, and the like. Examples of themonobasic organic acid include butyric acid, isobutyric acid, caproicacid, 2-ethylbutyric acid, heptanoic acid, n-octylic acid,2-ethylhexanoic acid, n-nonylic acid, decylic acid, benzoic acid and thelike.

Examples of the polybasic organic acid ester include an ester compoundof a polybasic organic acid and an alcohol having a linear or branchedstructure of 4 to 8 carbon atoms. Examples of the polybasic organic acidinclude adipic acid, sebacic acid, azelaic acid, and the like.

Examples of the organic ester plasticizer include triethylene glycoldi-2-ethylpropanoate, triethylene glycol di-2-ethylbutyrate, triethyleneglycol di-2-ethylhexanoate, triethylene glycol dicaprylate, triethyleneglycol di-n-octanoate, triethylene glycol di-n-heptanoate, tetraethyleneglycol di-n-heptanoate, dibutyl sebacate, dioctyl azelate, dibutylcarbitol adipate, ethylene glycol di-2-ethylbutyrate, 1,3-propyleneglycol di-2-ethylbutyrate, 1,4-butylene glycol di-2-ethylbutyrate,diethylene glycol di-2-ethylbutyrate, diethylene glycoldi-2-ethylhexanoate, dipropylene glycol di-2-ethylbutyrate, triethyleneglycol di-2-ethylpentanoate, tetraethylene glycol di-2-ethylbutyrate,diethylene glycol dicaprylate, diethylene glycol dibenzoate, dipropyleneglycol dibenzoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyladipate, a mixture of heptyl adipate and nonyl adipate, diisononyladipate, diisodecyl adipate, heptyl nonyl adipate, dibutyl sebacate,oil-modified sebacic alkyds, a mixture of a phosphoric acid ester and anadipic acid ester, and the like. Organic ester plasticizers other thanthese may be used. Other adipic acid esters other than theabove-described adipic acid esters may be used.

Examples of the organic phosphate plasticizer include tributoxyethylphosphate, isodecyl phenyl phosphate, triisopropyl phosphate, and thelike.

It is preferred that the plasticizer be a diester plasticizerrepresented by the following formula (1).

[Chemical 1]

In the foregoing formula (1), R1 and R2 each represent an organic groupwith 5 to 10 carbon atoms, R3 represents an ethylene group, anisopropylene group, or an n-propylene group, and p represents an integerof 3 to 10. It is preferred that R1 and R2 in the foregoing formula (1)each be an organic group with 6 to 10 carbon atoms.

It is preferred that the plasticizer include triethylene glycoldi-2-ethylhexanoate (3GO), triethylene glycol di-2-ethylbutyrate (3GH)or triethylene glycol di-2-ethylpropanoate. It is more preferred thatthe plasticizer include triethylene glycol di-2-ethylhexanoate (3GO) ortriethylene glycol di-2-ethylbutyrate (3GH), and it is further preferredthat the plasticizer include triethylene glycol di-2-ethylhexanoate.

In the interlayer film, a content of the plasticizer (0) relative to 100parts by weight of the resin (0) (when the resin (0) is thermoplasticresin (0), 100 parts by weight of the thermoplastic resin (0); when theresin (0) is polyvinyl acetal resin (0), 100 parts by weight of thepolyvinyl acetal resin (0)) is referred to as content (0). The content(0) is preferably 25 parts by weight or more, more preferably 30 partsby weight or more, and is preferably 100 parts by weight or less, morepreferably 60 parts by weight or less, further preferably 50 parts byweight or less. When the content (0) is the above lower limit or more,the penetration resistance of laminated glass is further enhanced. Whenthe content (0) is the above upper limit or less, the transparency ofthe interlayer film is further enhanced.

In the first layer, a content of the plasticizer (1) relative to 100parts by weight of the resin (1) (when the resin (1) is thermoplasticresin (1), 100 parts by weight of the thermoplastic resin (1); when theresin (1) is polyvinyl acetal resin (1), 100 parts by weight of thepolyvinyl acetal resin (1)) is referred to as content (1). The content(1) is preferably 50 parts by weight or more, more preferably 55 partsby weight or more, further preferably 60 parts by weight or more, and ispreferably 100 parts by weight or less, more preferably 90 parts byweight or less, further preferably 85 parts by weight or less,especially preferably 80 parts by weight or less. When the content (1)is the above lower limit or more, the flexibility of the interlayer filmis enhanced and the handling of the interlayer film is facilitated. Whenthe content (1) is the above upper limit or less, the penetrationresistance of laminated glass is further enhanced.

In the second layer, a content of the plasticizer (2) relative to 100parts by weight of the resin (2) (when the resin (2) is thermoplasticresin (2), 100 parts by weight of the thermoplastic resin (2); when theresin (2) is polyvinyl acetal resin (2), 100 parts by weight of thepolyvinyl acetal resin (2)) is referred to as content (2). In the thirdlayer, a content of the plasticizer (3) relative to 100 parts by weightof the resin (3) (when the resin (3) is thermoplastic resin (3), 100parts by weight of the thermoplastic resin (3); when the resin (3) ispolyvinyl acetal resin (3), 100 parts by weight of the polyvinyl acetalresin (3)) is referred to as content (3). Each of the content (2) andthe content (3) is preferably 10 parts by weight or more, morepreferably 15 parts by weight or more, further preferably 20 parts byweight or more, especially preferably 24 parts by weight or more, andmost preferably 25 parts by weight or more. Each of the content (2) andthe content (3) is preferably 45 parts by weight or less, morepreferably 40 parts by weight or less, further preferably 35 parts byweight or less, especially preferably 32 parts by weight or less, andmost preferably 30 parts by weight or less. When the content (2) and thecontent (3) are the above lower limit or more, the flexibility of theinterlayer film is enhanced and the handling of the interlayer film isfacilitated. When the content (2) and the content (3) are the aboveupper limit or less, the penetration resistance of laminated glass isfurther enhanced.

For the purpose of enhancing the sound insulating properties oflaminated glass, it is preferred that the content (1) be larger than thecontent (2) and it is preferred that the content (1) be larger than thecontent (3).

From the viewpoint of further enhancing the sound insulating property oflaminated glass, each of the absolute value of difference between thecontent (2) and the content (1) and the absolute value of differencebetween the content (3) and the content (1) is preferably 10 parts byweight or more, more preferably 15 parts by weight or more, and furtherpreferably 20 parts by weight or more. Each of the absolute value ofdifference between the content (2) and the content (1) and the absolutevalue of difference between the content (3) and the content (1) ispreferably 80 parts by weight or less, more preferably 75 parts byweight or less, further preferably 70 parts by weight or less.

(Heat Shielding Substance)

It is preferred that the interlayer film contain a heat shieldingsubstance (heat shielding compound). It is preferred that the firstlayer contain a heat shielding substance. It is preferred that thesecond layer contain a heat shielding substance. It is preferred thatthe third layer contain a heat shielding substance. One kind of the heatshielding substance may be used alone, and two or more kinds thereof maybe used in combination.

It is preferred that the heat shielding substance contain at least onekind of Ingredient X among a phthalocyanine compound, a naphthalocyaninecompound, and an anthracyanine compound or contain heat shieldingparticles. In this case, the heat shielding compound may be constitutedof both of the Ingredient X and the heat shielding particles.

Ingredient X:

It is preferred that the interlayer film include at least one kind ofIngredient X among a phthalocyanine compound, a naphthalocyaninecompound, and an anthracyanine compound. It is preferred that the firstlayer contain the Ingredient X. It is preferred that the second layercontain the Ingredient X. It is preferred that the third layer containthe Ingredient X. The Ingredient X is a heat shielding substance. Onekind of the Ingredient X may be used alone, and two or more kindsthereof may be used in combination.

The Ingredient X is not particularly limited. As the Ingredient X,conventionally known phthalocyanine compound, naphthalocyanine compoundand anthracyanine compound can be used.

Examples of the Ingredient X include phthalocyanine, a derivative ofphthalocyanine, naphthalocyanine, a derivative of naphthalocyanine,anthracyanine, and a derivative of anthracyanine, and the like. It ispreferred that each of the phthalocyanine compound and the derivative ofphthalocyanine have a phthalocyanine skeleton. It is preferred that eachof the naphthalocyanine compound and the derivative of naphthalocyaninehave a naphthalocyanine skeleton. It is preferred that each of theanthracyanine compound and the derivative of anthracyanine have ananthracyanine skeleton.

With regard to the interlayer film and laminated glass, from theviewpoint of further enhancing the heat shielding properties thereof, itis preferred that the Ingredient X be at least one kind selected fromthe group consisting of phthalocyanine, a derivative of phthalocyanine,naphthalocyanine and a derivative of naphthalocyanine, and it is morepreferred that the Ingredient X be at least one kind amongphthalocyanine and a derivative of phthalocyanine.

From the viewpoints of effectively enhancing the heat shieldingproperties and maintaining the visible light transmittance at a higherlevel over a long period of time, it is preferred that the ingredient Xcontain vanadium atoms or copper atoms. It is preferred that theIngredient X contain vanadium atoms and it is also preferred that theIngredient X contain copper atoms. It is more preferred that theIngredient X be at least one kind among phthalocyanine containingvanadium atoms or copper atoms and a derivative of phthalocyaninecontaining vanadium atoms or copper atoms. With regard to the interlayerfilm and laminated glass, from the viewpoint of still further enhancingthe heat shielding properties thereof, it is preferred that theIngredient X have a structural unit in which an oxygen atom is bonded toa vanadium atom.

In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the Ingredient X (a first layer, a second layer, or a thirdlayer), the content of the Ingredient X is preferably 0.001% by weightor more, more preferably 0.005% by weight or more, further preferably0.01% by weight or more, especially preferably 0.02% by weight or more.In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the Ingredient X (a first layer, a second layer, or a thirdlayer), the content of the Ingredient X is preferably 0.2% by weight orless, more preferably 0.1% by weight or less, further preferably 0.05%by weight or less, especially preferably 0.04% by weight or less. Whenthe content of the Ingredient X is the above lower limit or more and theabove upper limit or less, the heat shielding properties aresufficiently enhanced and the visible light transmittance issufficiently enhanced. For example, it is possible to make the visiblelight transmittance 70% or more.

Heat Shielding Particles:

It is preferred that the interlayer film contain heat shieldingparticles. It is preferred that the first layer contain the heatshielding particles. It is preferred that the second layer contain theheat shielding particles. It is preferred that the third layer containthe heat shielding particles. The heat shielding particle is of a heatshielding substance. By the use of heat shielding particles, infraredrays (heat rays) can be effectively cut off. One kind of the heatshielding particles may be used alone, and two or more kinds thereof maybe used in combination.

From the viewpoint of further enhancing the heat shielding properties oflaminated glass, it is more preferred that the heat shielding particlesbe metal oxide particles. It is preferred that the heat shieldingparticle be a particle (a metal oxide particle) formed from an oxide ofa metal.

The energy amount of an infrared ray with a wavelength of 780 nm orlonger which is longer than that of visible light is small as comparedwith an ultraviolet ray. However, the thermal action of infrared rays islarge, and when infrared rays are absorbed into a substance, heat isreleased from the substance. Accordingly, infrared rays are generallycalled heat rays. By the use of the heat shielding particles, infraredrays (heat rays) can be effectively cut off. In this connection, theheat shielding particle means a particle capable of absorbing infraredrays.

Specific examples of the heat shielding particles include metal oxideparticles such as aluminum-doped tin oxide particles, indium-doped tinoxide particles, antimony-doped tin oxide particles (ATO particles),gallium-doped zinc oxide particles (GZO particles), indium-doped zincoxide particles (IZO particles), aluminum-doped zinc oxide particles(AZO particles), niobium-doped titanium oxide particles, sodium-dopedtungsten oxide particles, cesium-doped tungsten oxide particles,thallium-doped tungsten oxide particles, rubidium-doped tungsten oxideparticles, tin-doped indium oxide particles (ITO particles), tin-dopedzinc oxide particles and silicon-doped zinc oxide particles, lanthanumhexaboride (LaB₆) particles, and the like. Heat shielding particlesother than these may be Since the heat ray shielding function is high,preferred are metal oxide particles, more preferred are ATO particles,GZO particles, IZO particles, ITO particles or tungsten oxide particles,and especially preferred are ITO particles or tungsten oxide particles.In particular, since the heat ray shielding function is high and theparticles are readily available, preferred are tin-doped indium oxideparticles (ITO particles), and also preferred are tungsten oxideparticles.

With regard to the interlayer film and laminated glass, from theviewpoint of further enhancing the heat shielding properties thereof, itis preferred that the tungsten oxide particles be metal-doped tungstenoxide particles. Examples of the “tungsten oxide particles” includemetal-doped tungsten oxide particles. Specifically, examples of themetal-doped tungsten oxide particles include sodium-doped tungsten oxideparticles, cesium-doped tungsten oxide particles, thallium-dopedtungsten oxide particles, rubidium-doped tungsten oxide particles, andthe like.

With regard to the interlayer film and laminated glass, from theviewpoint of further enhancing the heat shielding properties thereof,cesium-doped tungsten oxide particles are especially preferred. Withregard to the interlayer film and laminated glass, from the viewpoint ofstill further enhancing the heat shielding properties thereof, it ispreferred that the cesium-doped tungsten oxide particles be tungstenoxide particles represented by the formula: Cs_(0.33)WO₃.

The average particle diameter of the heat shielding particles ispreferably 0.01 μm or more, more preferably 0.02 μm or more, and ispreferably 0.1 μm or less and more preferably 0.05 μm or less. When theaverage particle diameter is the above lower limit or more, the heat rayshielding properties are sufficiently enhanced. When the averageparticle diameter is the above upper limit or less, the dispersibilityof heat shielding particles is enhanced.

The “average particle diameter” refers to the volume average particlediameter. The average particle diameter can be measured using a particlesize distribution measuring apparatus (“UPA-EX150” available fromNIKKISO CO., LTD.), or the like.

In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the heat shielding particles (a first layer, a second layer,or a third layer), each content of the heat shielding particles (inparticular, the content of tungsten oxide particles) is preferably 0.01%by weight or more, more preferably 0.1% by weight or more, furtherpreferably 1% by weight or more, especially preferably 1.5% by weight ormore. In 100% by weight of the interlayer film or in 100% by weight of alayer containing the heat shielding particles (a first layer, a secondlayer, or a third layer), each content of the heat shielding particles(in particular, the content of tungsten oxide particles) is preferably6% by weight or less, more preferably 5.5% by weight or less, furtherpreferably 4% by weight or less, especially preferably 3.5% by weight orless, most preferably 3% by weight or less. When the content of the heatshielding particles is the above lower limit or more and the above upperlimit or less, the heat shielding properties are sufficiently enhancedand the visible light transmittance is sufficiently enhanced.

(Metal Salt)

It is preferred that the interlayer film contain at least one kind ofmetal salt (hereinafter, sometimes described as Metal salt M) among analkali metal salt, an alkaline earth metal salt, and a magnesium salt.It is preferred that the first layer contain the Metal salt M. It ispreferred that the second layer contain the Metal salt M. It ispreferred that the third layer contain the Metal salt M. By the use ofthe Metal salt M, controlling the adhesivity between the interlayer filmand a lamination glass member such as a glass plate or the adhesivitybetween respective layers in the interlayer film is facilitated. Onekind of the Metal salt M may be used alone, and two or more kindsthereof may be used in combination.

It is preferred that the Metal salt M contain at least one kind of metalselected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr andBa. It is preferred that the metal salt included in the interlayer filmcontain at least one kind of metal among K and Mg.

Moreover, it is more preferred that the Metal salt M be an alkali metalsalt of an organic acid with 2 to 16 carbon atoms, an alkaline earthmetal salt of an organic acid with 2 to 16 carbon atoms, and a magnesiumsalt of an organic acid with 2 to 16 carbon atoms, and it is furtherpreferred that the Metal salt M be a magnesium carboxylate with 2 to 16carbon atoms or a potassium carboxylate with 2 to 16 carbon atoms.

Examples of the magnesium carboxylate with 2 to 16 carbon atoms and thepotassium carboxylate with 2 to 16 carbon atoms include magnesiumacetate, potassium acetate, magnesium propionate, potassium propionate,magnesium 2-ethylbutyrate, potassium 2-ethylbutanoate, magnesium2-ethylhexanoate, potassium 2-ethylhexanoate, and the like.

The total of the contents of Mg and K in an interlayer film containingthe Metal salt M or a layer containing the Metal salt M (a first layer,a second layer, or a third layer) is preferably 5 ppm or more, morepreferably 10 ppm or more, and further preferably 20 ppm or more and ispreferably 300 ppm or less, more preferably 250 ppm or less, and furtherpreferably 200 ppm or less. When the total of the contents of Mg and Kis the above lower limit or more and the above upper limit or less, theadhesivity between the interlayer film and a glass plate or theadhesivity between respective layers in the interlayer film can befurther well controlled.

(Ultraviolet Ray Screening Agent)

It is preferred that the interlayer film contain an ultraviolet rayscreening agent. It is preferred that the first layer contain anultraviolet ray screening agent. It is preferred that the second layercontain an ultraviolet ray screening agent. It is preferred that thethird layer contain an ultraviolet ray screening agent. By the use of anultraviolet ray screening agent, even when the interlayer film and thelaminated glass are used for a long period of time, the visible lighttransmittance becomes further hard to be lowered. One kind of theultraviolet ray screening agent may be used alone, and two or more kindsthereof may be used in combination.

Examples of the ultraviolet ray screening agent include an ultravioletray absorber. It is preferred that the ultraviolet ray screening agentbe an ultraviolet ray absorber.

Examples of the ultraviolet ray screening agent include an ultravioletray screening agent containing a metal atom, an ultraviolet rayscreening agent containing a metal oxide, an ultraviolet ray screeningagent having a benzotriazole structure (a benzotriazole compound), anultraviolet ray screening agent having a benzophenone structure (abenzophenone compound), an ultraviolet ray screening agent having atriazine structure (a triazine compound), an ultraviolet ray screeningagent having a malonic acid ester structure (a malonic acid estercompound), an ultraviolet ray screening agent having an oxanilidestructure (an oxanilide compound), an ultraviolet ray screening agenthaving a benzoate structure (a benzoate compound), and the like.

Examples of the ultraviolet ray screening agent containing a metal atominclude platinum particles, particles in which the surface of platinumparticles is coated with silica, palladium particles, particles in whichthe surface of palladium particles is coated with silica, and the like.It is preferred that the ultraviolet ray screening agent not be heatshielding particles.

The ultraviolet ray screening agent is preferably an ultraviolet rayscreening agent having a benzotriazole structure, an ultraviolet rayscreening agent having a benzophenone structure, an ultraviolet rayscreening agent having a triazine structure, or an ultraviolet rayscreening agent having a benzoate structure. The ultraviolet rayscreening agent is more preferably an ultraviolet ray screening agenthaving a benzotriazole structure or an ultraviolet ray screening agenthaving a benzophenone structure, and is further preferably anultraviolet ray screening agent having a benzotriazole structure.

Examples of the ultraviolet ray screening agent containing a metal oxideinclude zinc oxide, titanium oxide, cerium oxide, and the like.Furthermore, with regard to the ultraviolet ray screening agentcontaining a metal oxide, the surface thereof may be coated with anymaterial. Examples of the coating material for the surface of theultraviolet ray screening agent containing a metal oxide include aninsulating metal oxide, a hydrolyzable organosilicon compound, asilicone compound, and the like.

Examples of the insulating metal oxide include silica, alumina,zirconia, and the like. For example, the insulating metal oxide has aband-gap energy of 5.0 eV or more.

Examples of the ultraviolet ray screening agent having a benzotriazolestructure include 2-(2′-hydroxy-5′-methylphenyl)benzotriazole (“TinuvinP” available from BASF Japan Ltd.),2-(2′-hydroxy-3′,5′-di-t-butylphenyl)benzotriazole (“Tinuvin 320”available from BASF Japan Ltd.),2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole (“Tinuvin326” available from BASF Japan Ltd.),2-(2′-hydroxy-3′,5′-di-amylphenyl)benzotriazole (“Tinuvin 328” availablefrom BASF Japan Ltd.), and the like. It is preferred that theultraviolet ray screening agent be an ultraviolet ray screening agenthaving a benzotriazole structure containing a halogen atom, and it ismore preferred that the ultraviolet ray screening agent be anultraviolet ray screening agent having a benzotriazole structurecontaining a chlorine atom, because those are excellent in ultravioletray screening performance.

Examples of the ultraviolet ray screening agent having a benzophenonestructure include octabenzone (“Chimassorb 81” available from BASF JapanLtd.), and the like.

Examples of the ultraviolet ray screening agent having a triazinestructure include “LA-F70” available from ADEKA CORPORATION,2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol (“Tinuvin1577FF” available from BASF Japan Ltd.), and the like.

Examples of the ultraviolet ray screening agent having a malonic acidester structure include dimethyl 2-(p-methoxybenzylidene)malonate,tetraethyl-2,2-(1,4-phenylenedimethylidene)bismalonate,2-(p-methoxybenzylidene)-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)malonate,and the like.

Examples of a commercial product of the ultraviolet ray screening agenthaving a malonic acid ester structure include Hostavin B-CAP, HostavinPR-25 and Hostavin PR-31 (any of these is available from Clariant JapanK.K.).

Examples of the ultraviolet ray screening agent having an oxanilidestructure include a kind of oxalic acid diamide having a substitutedaryl group and the like on the nitrogen atom such asN-(2-ethylphenyl)-N′-(2-ethoxy-5-t-butylphenyl)oxalic acid diamide,N-(2-ethylphenyl)-N′-(2-ethoxy-phenyl)oxalic acid diamide and2-ethyl-2′-ethoxy-oxanilide (“Sanduvor VSU” available from ClariantJapan K.K.).

Examples of the ultraviolet ray screening agent having a benzoatestructure include2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (“Tinuvin120” available from BASF Japan Ltd.), and the like.

In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the ultraviolet ray screening agent (a first layer, a secondlayer, or a third layer), the content of the ultraviolet ray screeningagent and the content of the benzotriazole compound are preferably 0.1%by weight or more, more preferably 0.2% by weight or more, furtherpreferably 0.3% by weight or more, especially preferably 0.5% by weightor more. In 100% by weight of the interlayer film or in 100% by weightof a layer containing the ultraviolet ray screening agent (a firstlayer, a second layer, or a third layer), the content of the ultravioletray screening agent and the content of the benzotriazole compound arepreferably 2.5% by weight or less, more preferably 2% by weight or less,further preferably 1% by weight or less, especially preferably 0.8% byweight or less. When the content of the ultraviolet ray screening agentis the above-described lower limit or more and the above-described upperlimit or less, deterioration in visible light transmittance after alapse of a period can be further suppressed. In particular, by settingthe content of the ultraviolet ray screening agent to be 0.2% by weightor more in 100% by weight of a layer containing the ultraviolet rayscreening agent, with regard to the interlayer film and laminated glass,the lowering in visible light transmittance thereof after the lapse of acertain period of time can be significantly suppressed.

(Oxidation Inhibitor)

It is preferred that the interlayer film contain an oxidation inhibitor.It is preferred that the first layer contain an oxidation inhibitor. Itis preferred that the second layer contain an oxidation inhibitor. It ispreferred that the third layer contain an oxidation inhibitor. One kindof the oxidation inhibitor may be used alone, and two or more kindsthereof may be used in combination.

Examples of the oxidation inhibitor include a phenol-based oxidationinhibitor, a sulfur-based oxidation inhibitor, a phosphorus-basedoxidation inhibitor, and the like. The phenol-based oxidation inhibitoris an oxidation inhibitor having a phenol skeleton. The sulfur-basedoxidation inhibitor is an oxidation inhibitor containing a sulfur atom.The phosphorus-based oxidation inhibitor is an oxidation inhibitorcontaining a phosphorus atom.

It is preferred that the oxidation inhibitor be a phenol-based oxidationinhibitor or a phosphorus-based oxidation inhibitor.

Examples of the phenol-based oxidation inhibitor include2,6-di-t-butyl-p-cresol (BHT), butyl hydroxyanisole (BHA),2,6-di-t-butyl-4-ethylphenol, stearylβ-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,2,2′-methylenebis-(4-methyl-6-butylphenol),2,2′-methylenebis-(4-ethyl-6-t-butylphenol),4,4′-butylidene-bis-(3-methyl-6-t-butylphenol),1,1,3-tris-(2-methyl-hydroxy-5-t-butylphenyl)butane,tetrakis[methylene-3-(3′,5′-butyl-4-hydroxyphenyl)propionate]methane,1,3,3-tris-(2-methyl-4-hydroxy-5-t-butylphenol)butane,1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene,bis(3,3′-t-butylphenol)butyric acid glycol ester,bis(3-t-butyl-4-hydroxy-5-methylbenzenepropanoicacid)ethylenebis(oxyethylene), and the like. One kind or two or morekinds among these oxidation inhibitors are preferably used.

Examples of the phosphorus-based oxidation inhibitor include tridecylphosphite, tris(tridecyl) phosphite, triphenyl phosphite, trinonylphenylphosphite, bis(tridecyl)pentaerithritol diphosphite,bis(decyl)pentaerithritol diphosphate, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4-di-t-butyl-6-methylphenyl)ethyl ester phosphorousacid,2,2′-methylenebis(4,6-di-t-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphorus,and the like. One kind or two or more kinds among these oxidationinhibitors are preferably used.

Examples of a commercial product of the oxidation inhibitor include“IRGANOX 245” available from BASF Japan Ltd., “IRGAFOS 168” availablefrom BASF Japan Ltd., “IRGAFOS 38” available from BASF Japan Ltd.,“Sumilizer BHT” available from Sumitomo Chemical Co., Ltd., “H-BHT”available from Sakai Chemical Industry Co., Ltd., “IRGANOX 1010”available from BASF Japan Ltd., and the like.

With regard to the interlayer film and laminated glass, in order tomaintain high visible light transmittance thereof over a long period oftime, it is preferred that the content of the oxidation inhibitor be0.1% by weight or more in 100% by weight of the interlayer film or in100% by weight of the layer containing the oxidation inhibitor (a firstlayer, a second layer or a third layer). Moreover, since an effectcommensurate with the addition of an oxidation inhibitor is notattained, it is preferred that the content of the oxidation inhibitor be2% by weight or less in 100% by weight of the interlayer film or in 100%by weight of the layer containing the oxidation inhibitor.

(Other Ingredients)

Each of the interlayer film, the first layer, the second layer, and thethird layer may contain additives such as a coupling agent, a dispersingagent, a surfactant, a flame retardant, an antistatic agent, a pigment,a dye, an adhesivity adjusting agent other than metal salt, amoisture-resistance agent, a fluorescent brightening agent, and aninfrared ray absorber, as necessary. One kind of these additives may beused alone, and two or more kinds thereof may be used in combination.

(Laminated glass)

FIG. 3 is a sectional view showing an example of laminated glassprepared with the interlayer film for laminated glass shown in FIG. 1 .

A laminated glass 21 shown in FIG. 3 is provided with the interlayerfilm 11, a first lamination glass member 22, and a second laminationglass member 23. The interlayer film 11 is arranged between the firstlamination glass member 22 and the second lamination glass member 23 tobe sandwiched therebetween. The first lamination glass member 22 isarranged on a first surface of the interlayer film 11. The secondlamination glass member 23 is arranged on a second surface opposite tothe first surface of the interlayer film 11.

Examples of the lamination glass member include a glass plate, a PET(polyethylene terephthalate) film, and the like. As the laminated glass,laminated glass in which an interlayer film is sandwiched between aglass plate and a PET film or the like, as well as laminated glass inwhich an interlayer film is sandwiched between two glass plates, isincluded. The laminated glass is a laminate provided with a glass plate,and it is preferred that at least one glass plate be used. It ispreferred that each of the first lamination glass member and the secondlamination glass member be a glass plate or a PET (polyethyleneterephthalate) film and the interlayer film include at least one glassplate as the first lamination glass member or the second laminationglass member. It is especially preferred that both of the firstlamination glass member and the second lamination glass member be glassplates.

Examples of the glass plate include a sheet of inorganic glass and asheet of organic glass. Examples of the inorganic glass include floatplate glass, heat ray-absorbing plate glass, heat ray-reflecting plateglass, polished plate glass, figured glass, wired plate glass, greenglass, and the like. The organic glass is synthetic resin glasssubstituted for inorganic glass. Examples of the organic glass include apolycarbonate plate, a poly(meth)acrylic resin plate, and the like.Examples of the poly(meth)acrylic resin plate include a polymethyl(meth)acrylate plate, and the like.

Although respective thicknesses of the first lamination glass member andthe second lamination glass member are not particularly limited, thethickness is preferably 1 mm or more and is preferably 5 mm or less.When the lamination glass member is a glass plate, the thickness of theglass plate is preferably 1 mm or more and is preferably 5 mm or less.When the lamination glass member is a PET film, the thickness of the PETfilm is preferably 0.03 mm or more and is preferably 0.5 mm or less.

The method for producing the laminated glass is not particularlylimited. First, the interlayer film is sandwiched between the firstlamination glass member and the second lamination glass member to obtaina laminate. Then, for example, by passing the obtained laminate throughpressure rolls or subjecting the obtained laminate to decompressionsuction in a rubber bag, the air remaining between the first laminationglass member and the interlayer film, and between the second laminationglass member and the interlayer film is removed. Then, the laminate ispreliminarily bonded together at about 70 to 110° C. to obtain apreliminarily press-bonded laminate. Next, by putting the preliminarilypress-bonded laminate into an autoclave or by pressing the laminate, thelaminate is press-bonded at about 120 to 150° C. and under a pressure of1 to 1.5 MPa. In this way, laminated glass can be obtained.

The laminated glass can be used for automobiles, railway vehicles,aircraft, ships, buildings, and the like. It is preferred that thelaminated glass be laminated glass for building or for vehicles and itis more preferred that the laminated glass be laminated glass forvehicles. The laminated glass can also be used for applications otherthan these applications. The laminated glass can be used for awindshield, side glass, rear glass, or roof glass of an automobile, andthe like. Since the laminated glass is high in heat shielding propertiesand is high in visible light transmittance, the laminated glass issuitably used for automobiles.

The laminated glass is a kind of laminated glass serving as a head-updisplay (HUD). In the laminated glass, measured information such as thespeed which is sent from a control unit and the like can be projectedonto the windshield from a display unit of the instrumental panel. Assuch, without making a driver of an automobile move his or her visualfield downward, a front visual field and measured information can bevisually recognized simultaneously.

Hereinafter, the present invention will be described in more detail withreference to examples and comparative examples. The present invention isnot limited only to these examples.

In polyvinyl acetal resins used, n-butyraldehyde which has 4 carbonatoms is used for the acetalization. With regard to the polyvinyl acetalresin, the acetalization degree (the butyralization degree), theacetylation degree and the content of the hydroxyl group were measuredby a method in accordance with JIS K6728 “Testing methods for polyvinylbutyral”. In this connection, even in the cases of being measuredaccording to ASTM D1396-92, numerical values similar to those obtainedby a method in accordance with JIS K6728 “Testing methods for polyvinylbutyral” were exhibited.

Example 1

Preparation of Composition for Forming First Layer:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming a first layer. Otheringredients were added to the polyvinyl acetal resin.

Polyvinyl acetal resin (content of hydroxyl group: 22% by mole,acetylation degree: 13% by mole, acetalization degree: 65% by mole): 100parts by weight

Triethylene glycol di-2-ethylhexanoate (3GO): 60 parts by weight

Tinuvin 326(2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole,“Tinuvin 326” available from BASF Japan Ltd.): 0.2 parts by weight

BHT (2,6-di-t-butyl-p-cresol): 0.2 parts by weight

Preparation of Composition for Forming Second Layer and Third Layer:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming a second layer and athird layer. Other ingredients were added to the polyvinyl acetal resin.

Polyvinyl acetal resin (content of hydroxyl group: 30.5% by mole,acetylation degree: 1% by mole, acetalization degree: 68.5% by mole):100 parts by weight

Triethylene glycol di-2-ethylhexanoate (3GO): 38 parts by weight

Tinuvin 326(2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole,“Tinuvin 326” available from BASF Japan Ltd.): 0.2 parts by weight

BHT (2,6-di-t-butyl-p-cresol): 0.2 parts by weight

Preparation of Interlayer Film:

The composition for forming the first layer, and the composition forforming the second layer and the third layer were coextruded by using aco-extruder. At this time, the temperature of the lip die was adjustedwithin the range of 100° C. to 280° C. so that a temperature gradientwas provided while setting the end part having a smaller thickness ofthe entire interlayer film in the width direction as a low temperatureside, and the end part having a larger thickness of the entireinterlayer film as a high temperature side. The gap of the lip wasadjusted within the range of 1.0 to 4.0 mm so that the difference inspeed of rolls through which the resin film discharged from the lip diepasses up to winding was 15% or less. The roll through which the resinfilm discharged from the lip die first passes was installed below thedie and previous to the die in the machine direction. The extrudingamount from the extruder was 700 kg/h. The speed of the roll throughwhich the resin film first passes was adjusted to 7 m/minute. In Example1, after extrusion molding of the interlayer film, the interlayer filmwas heated and retained at 100° C. to 150° C. for 5 minutes or less, andthen returned to the normal temperature. A wedge-like interlayer filmhaving a multilayer structure of the second layer/the first layer/thethird layer was prepared. The interlayer film obtained in each ofExample 1, later-described Examples 2, 3 and Comparative Example 1 has aminimum thickness at one end and has a maximum thickness at the otherend.

Examples 2, 3 and Comparative Example 1

An interlayer film was obtained in the same manner as in Example 1except that the minimum thickness, the maximum thickness, the wedgeangle and the partial wedge angles in the interlayer film were set asshown in the following Table 1. In Example 2 and Comparative Example 1,the same kinds of the ultraviolet ray screening agent and the oxidationinhibitor as those in Example 1 were mixed in the same mixing amount asthat in Example 1 (0.2 parts by weight relative to 100 parts by weightof the polyvinyl acetal resin).

In Examples 2, 3 and Comparative Example 1, the temperature and thetemperature gradient of the lip die, extruding conditions, difference inspeed of rolls through which the resin film discharged from the lip diepasses up to winding, and the speed of the roll through which the resinfilm first passes were changed.

Example 4

Preparation of Composition for Forming Single-Layered Interlayer Film:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming a single-layeredinterlayer film. Other ingredients were added to the polyvinyl acetalresin.

Polyvinyl acetal resin (content of hydroxyl group: 30.5% by mole,acetylation degree: 1% by mole, acetalization degree: 68.5% by mole):100 parts by weight

Triethylene glycol di-2-ethylhexanoate (3GO): 40 parts by weight

Tinuvin 326(2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole,“Tinuvin 326” available from BASF Japan Ltd.): 0.2 parts by weight

BHT (2,6-di-t-butyl-p-cresol): 0.2 parts by weight

The composition for forming a single-layered interlayer film wasextruded by using an extruder. At this time, the temperature of the lipdie was adjusted within the range of 100° C. to 280° C. so that atemperature gradient was provided while setting the end part having asmaller thickness of the entire interlayer film in the width directionas a low temperature side, and the end part having a larger thickness ofthe entire interlayer film as a high temperature side. The gap of thelip was adjusted within the range of 1.0 to 4.0 mm. The difference inspeed of rolls through which the resin film discharged from the lip diepasses up to winding was set to be 15% or less. The roll through whichthe resin discharged from the lip die first passes was installed belowthe die and previous to the die in the machine direction, the extrudingamount from the extruder was adjusted to 700 kg/h, and the speed of theroll through which the resin film first passes was adjusted to 7m/minute. In Example 4, after extrusion molding of the interlayer film,the interlayer film was heated and retained at 100° C. to 150° C. for 5minutes or less, to prepare a single-layered interlayer film. Theinterlayer film obtained in each of Example 4 and the later-describedExample 5 has a minimum thickness at one end and has a maximum thicknessat the other end.

Example 5 and Comparative Example 2

An interlayer film and a roll body were obtained in the same manner asin Example 4 except that the minimum thickness, the maximum thickness,the distance from one end to the other end, the standard deviation of 11partial wedge angles, and the mean of 11 partial wedge angles in theinterlayer film were set as shown in the following Table 2. In Example 5and Comparative Example 2, the same kinds of the ultraviolet rayscreening agent and the oxidation inhibitor as those in Example 4 weremixed in the same mixing amount as that in Example 4 (0.2 parts byweight relative to 100 parts by weight of the polyvinyl acetal resin).

(Evaluation)

(1) Measurement of Partial Wedge Angles

In the obtained interlayer film, a first partial wedge angle (θ1) ineach first partial region (X1) of (8+0.2×A) cm to (12+0.2×A) cm from oneend of the interlayer film (A is an integer of 0 to 249) was calculated.

In the obtained interlayer film, a second partial wedge angle (θ2) ineach second partial region (X2) of (9+0.2×A) cm to (11+0.2×A) cm fromone end of the interlayer film (A is an integer of 0 to 249) wascalculated.

In the obtained interlayer film, a third partial wedge angle (θ3) ineach third partial region (X3) of (9.5+0.2×A) cm to (10.5+0.2×A) cm fromone end of the interlayer film (A is an integer of 0 to 249) wascalculated.

Partial wedge angle was measured with “TOF-4R” available from YamabunElectronics Co., Ltd. in the method as described above.

The region for display in Examples and Comparative Examples is a regionof 8 cm to 61.8 cm from one end of the interlayer film.

(2) Double Images

A pair of glass plates (clear glass, the size of 510 mm×910 mm, 2.0 mmin thickness) was prepared. An interlayer film with a size correspondingto the size of the glass plate was sandwiched between the pair of glassplates to obtain a laminate. As shown in FIG. 5 , the obtained laminatewas fitted into a frame of an EPDM-made rubber tube (frame member). Therubber tube had a width of 15 mm. Next, the laminate fitted into a frameof an EPDM-made rubber tube was preliminarily press-bonded by a vacuumbag method. The preliminarily press-bonded laminate was subjected topress-bonding at 150° C. and a pressure of 1.2 MPa with the use of anautoclave to obtain a sheet of laminated glass.

The obtained sheet of laminated glass was installed at a position of thewindshield. The information to be displayed, which is emitted from adisplay unit (focal distance: 2 m, 3 m, and 4 m) installed below thelaminated glass, was reflected by the sheet of laminated glass tovisually confirm the presence or absence of double images at aprescribed position (the entire region for display). The double imageswere judged according to the following criteria,

[Criteria for Judgment on Double Images]

∘∘: Double images are not confirmed.

∘: Double images are confirmed very slightly and are at a level causingno problem in practical use.

x: Not corresponding to the criteria of ∘∘ and ∘.

The details and the results are shown in the following Tables 1 and 2.

TABLE 1 Comparative Example Example Example Example 1 2 1 3 Minimumthickness in interlayer film μm 800 800 800 800 Maximum thickness ininterlayer film μm 1200 2300 1200 1200 Wedge angle of interlayer film asa mrad 0.4 1.5 0.4 0.4 whole(θ) Evaluation Maximum value among firstmrad 0.6 1.7 0.8 0.45 partial wedge angle (θ1) Minimum value among firstmrad 0.2 1.3 0.2 0.3 partial wedge angle (θ1) Absolute value ofdifference mrad 0.4 0.4 0.6 0.15 between maximum value among firstpartial wedge angle (θ1) and minimum value among first partial wedgeangle (θ1) Maximum value among second mrad 0.6 1.8 0.9 0.5 partial wedgeangle (θ2) Minimum value among second mrad 0.2 1.4 0.2 0.3 partial wedgeangle (θ2) Absolute value of difference mrad 0.4 0.4 0.7 0.2 betweenmaximum value among second partial wedge angle (θ2) and minimum valueamong second partial wedge angle (θ2) Maximum value among third mrad 0.61.6 1.2 0.5 partial wedge angle (θ3) Minimum value among third mrad 0.21.2 0.4 0.25 partial wedge angle (θ3) Absolute value of difference mrad0.4 0.4 0.8 0.25 between maximum value among third partial wedge angle(θ3) and minimum value among third partial wedge angle (θ3) Doubleimages ∘∘ ∘∘ ∘ ∘∘ (focal distance: 2 m) Double images ∘∘ ∘∘ x ∘∘ (focaldistance: 3 m) Double images ∘ ∘ x ∘∘ (focal distance: 4 m)

TABLE 2 Comparative Example Example 4 2 Minimum thickness in interlayerfilm μm 760 760 Maximum thickness in interlayer film μm 1160 1160 Wedgeangle of interlayer film as a whole(θ) mrad 0.4 0.4 Evaluation Maximumvalue among first mrad 0.6 0.8 partial wedge angle (θ1) Minimum valueamong first mrad 0.2 02 partial wedge angle (θ1) Absolute value ofdifference mrad 0.4 0.6 between maximum value among first partial wedgeangle (θ1) and minimum value among first partial wedge angle (θ1)Maximum value among second mrad 0.6 0.9 partial wedge angle (θ2) Minimumvalue among second mrad 0.2 0.2 partial wedge angle (θ2) Absolute valueof difference mrad 0.4 0.7 between maximum value among second partialwedge angle (θ2) and minimum value among second partial wedge angle (θ2)Maximum value among third mrad 0.6 1.2 partial wedge angle (θ3) Minimumvalue among third mrad 0.2 0.4 partial wedge angle (θ3) Absolute valueof difference mrad 0.4 0.8 between maximum value among third partialwedge angle (θ3) and minimum value among third partial wedge angle (θ3)Double images (focal distance: oo o 2 m) Double images (focal distance:oo x 3 m) Double images (focal distance: o x 4 m)

In this connection, sheets of laminated glass prepared with interlayerfilms obtained in Examples 1 to 3 respectively were evaluated for thesound insulating properties with sound transmission losses, and as aresult, it was confirmed that the sheets were excellent in soundinsulating properties.

EXPLANATION OF SYMBOLS

-   -   1, 1A: First layer    -   1Aa: Portion having sectional shape in thickness direction of        rectangular shape    -   1Ab: Portion having sectional shape in thickness direction of        wedge-like shape    -   2: Second layer    -   3: Third layer    -   11, 11A: Interlayer film    -   11 a: One end    -   11 b: Other end    -   11Aa: Portion having sectional shape in thickness direction of        rectangular shape    -   11Ab: Portion having sectional shape in thickness direction of        wedge-like shape    -   21: Laminated glass    -   22: First lamination glass member    -   23: Second lamination glass member    -   R1: Region for display    -   R2: Surrounding region    -   R3: Shading region    -   51: Roll body    -   61: Winding core

The invention claimed is:
 1. An interlayer film for laminated glass foruse in laminated glass that is a head-up display, the interlayer filmhaving one end, and the other end being at the opposite side of the oneend, the other end having a thickness larger than a thickness of the oneend, the interlayer film having a region for display corresponding to adisplay region of the head-up display, when points are selected at 2 mmintervals while taking a position of 2 cm from an end part of the oneend side toward the other end of the region for display as a startpoint, and a position of 2 cm from an end part of the other end sidetoward the one end of the region for display as an end point, and firstpartial wedge angles are calculated in respective first partial regionsof 40 mm in the direction connecting the one end and the other endcentered at respective selected points, an absolute value of differencebetween the maximum value among all the first partial wedge angle valuesand the minimum value among all the first partial wedge angle valuesbeing 0.15 mrad or more and 0.4 mrad or less, the interlayer film as awhole having a wedge angle of 0.1 mrad or more, the interlayer filmhaving the region for display in a region between a position (1) being 8cm away from the one end in the direction connecting the one end and theother end of the interlayer film and a position (2) being 61.8 cm awayfrom the one end in the direction connecting the one end and the otherend of the interlayer film, the positions (1) and (2) being positionsinside the interlayer film, the thickness in the whole of the region fordisplay of the interlayer film increases in such a manner that thethickness of an end part of the region for display in the other end sideof the interlayer film is larger than that in the one end side of theinterlayer film.
 2. The interlayer film for laminated glass according toclaim 1, wherein when points are selected at 2 mm intervals while takinga position of 2 cm from an end part of the one end side toward the otherend of the region for display as a start point, and a position of 2 cmfrom an end part of the other end side toward the one end of the regionfor display as an end point, and second partial wedge angles arecalculated in respective second partial regions of 20 mm in thedirection connecting the one end and the other end centered atrespective selected points, an absolute value of difference between themaximum value among all the second partial wedge angle values and theminimum value among all the second partial wedge angle values is 0.4mrad or less.
 3. The interlayer film for laminated glass according toclaim 1, wherein when points are selected at 2 mm intervals while takinga position of 2 cm from an end part of the one end side toward the otherend of the region for display as a start point, and a position of 2 cmfrom an end part of the other end side toward the one end of the regionfor display as an end point, and third partial wedge angles arecalculated in respective third partial regions of 10 mm in the directionconnecting the one end and the other end centered at respective selectedpoints, an absolute value of difference between the maximum value amongall the third partial wedge angle values and the minimum value among allthe third partial wedge angle values is 0.4 mrad or less.
 4. Aninterlayer film for laminated glass having one end and the other endbeing at opposite side of the one end, the other end having a thicknessof larger than a thickness of the one end, when 250 points are selectedat 2 mm intervals from a position of 10 cm from the one end toward theother end of the interlayer film, and 250 first partial wedge angles arecalculated in respective first partial regions of 40 mm in the directionconnecting the one end and the other end centered at respective 250points, an absolute value of difference between the maximum value amongthe 250 first partial wedge angle values and the minimum value among the250 first partial wedge angle values being 0.15 mrad or more and 0.4mrad or less, the interlayer film as whole having a wedge angle of 0.1mrad or more, the thickness in the whole of a region (A) between aposition (1) being 8 cm away from the one end in the directionconnecting the one end and the other end of the interlayer film and aposition (2) being 61.8 cm away from the one end in the directionconnecting the one end and the other end of the interlayer filmincreasing in such a manner that the thickness of an end part of theregion (A) in the position (2) is larger than that in the position (1),the positions (1) and (2) being positions inside the interlayer film. 5.The interlayer film for laminated glass according to claim 4, whereinwhen 250 points are selected at 2 mm intervals from a position of 1.0 cmfrom the one end toward the other end of the interlayer film, and 250second partial wedge angles are calculated in respective second partialregions of 20 mm in the direction connecting the one end and the otherend centered at respective 250 points, an absolute value of differencebetween the maximum value among the 250 second partial wedge anglevalues and the minimum value among the 250 second partial wedge anglevalues is 0.4 mrad or less.
 6. The interlayer film for laminated glassaccording to claim 4, wherein when 250 points are selected at 2 mmintervals from a position of 10 cm from the one end toward the other endof the interlayer film, and 250 third partial wedge angles arecalculated in respective third partial regions of 10 mm in the directionconnecting the one end and the other end centered at respective 250points, an absolute value of difference between the maximum value amongthe 250 third partial wedge angle values and the minimum value among the250 third partial wedge angle values is 0.4 mrad or less.
 7. Theinterlayer film for laminated glass according to claim 1, wherein themaximum value among all the first partial wedge angle values is 2.0 mrador less.
 8. The interlayer film for laminated glass according to claim2, wherein the maximum value among all the first partial wedge anglevalues is 2.0 mrad or less, and the maximum value among all the secondpartial wedge angle values is 2.0 mrad or less.
 9. The interlayer filmfor laminated glass according to claim 3, wherein the maximum valueamong all the first partial wedge angle values is 2.0 mrad or less, andthe maximum value among all the third partial wedge angle values is 2.0mrad or less.
 10. The interlayer film for laminated glass according toclaim 1, wherein the minimum value among all the first partial wedgeangle values is 0.1 mrad or more.
 11. The interlayer film for laminatedglass according to claim 2, wherein the minimum value among all thefirst partial wedge angle values is 0.1 mrad or more, and the minimumvalue among all the second partial wedge angle values is 0.1 mrad ormore.
 12. The interlayer film for laminated glass according to claimwherein the minimum value among all the first partial wedge angle valuesis 0.1 mrad or more, and the minimum value among all the third partialwedge angle values is 0.1 mrad or more.
 13. The interlayer film forlaminated glass according to claim 1, containing a thermoplastic resin.14. The interlayer film for laminated glass according to claim 1,containing a plasticizer.
 15. The interlayer film for laminated glassaccording to claim 1, comprising: a first layer; and a second layerarranged on a first surface side of the first layer.
 16. The interlayerfilm for laminated glass according to claim 15, wherein the first layercontains a polyvinyl acetal resin, the second layer contains a polyvinylacetal resin, and a content of a hydroxyl group of the polyvinyl acetalresin in the first layer is lower than a content of a hydroxyl group ofthe polyvinyl acetal resin in the second layer.
 17. The interlayer filmfor laminated glass according to claim 15, wherein the first layercontains a polyvinyl acetal resin, the second layer contains a polyvinylacetal resin, the first layer contains a plasticizer, the second layercontains a plasticizer, and a content of the plasticizer in the firstlayer relative to 100 parts by weight of the polyvinyl acetal resin inthe first layer is larger than a content of the plasticizer in thesecond layer relative to 100 parts by weight of the polyvinyl acetalresin in the second layer.
 18. A laminated glass, comprising: a firstlamination glass member; a second lamination glass member; and theinterlayer film for laminated glass according to claim 1, the interlayerfilm for laminated glass being arranged between the first laminationglass member and the second lamination glass member.
 19. The interlayerfilm for laminated glass according to claim 4, wherein the minimum valueamong the 250 first partial wedge angle values is 0.1 mrad or more. 20.The interlayer film for laminated glass according to claim 1, comprisingat least one selected from the group consisting of platinum particles,platinum particles coated with silica, palladium particles, andpalladium particles coated with silica.
 21. The interlayer film forlaminated glass according to claim 1, comprising a metal oxide having asurface coating comprising at least one selected from the groupconsisting of an insulating metal oxide, a hydrolyzable organosiliconcompound, and a silicone compound.
 22. The interlayer film for laminatedglass according to claim 1, the thickness in the whole of the region fordisplay of the interlayer film continuously increases.
 23. Theinterlayer film for laminated glass according to claim 4, the thicknessin the whole of the region (A) continuously increases.